<?xml version="1.0" encoding="utf-8"?>
<!DOCTYPE article PUBLIC "-//NLM//DTD Journal Publishing DTD v3.0 20080202//EN" "journalpublishing3.dtd">
<article xml:lang="en" article-type="research-article" xmlns:xlink="http://www.w3.org/1999/xlink" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">
<?release-delay 0|0?>
<front>
<journal-meta>
<journal-id journal-id-type="publisher-id">OL</journal-id>
<journal-title-group>
<journal-title>Oncology Letters</journal-title>
</journal-title-group>
<issn pub-type="ppub">1792-1074</issn>
<issn pub-type="epub">1792-1082</issn>
<publisher>
<publisher-name>D.A. Spandidos</publisher-name>
</publisher>
</journal-meta>
<article-meta>
<article-id pub-id-type="doi">10.3892/ol.2024.14275</article-id>
<article-id pub-id-type="publisher-id">OL-27-4-14275</article-id>
<article-categories>
<subj-group>
<subject>Articles</subject>
</subj-group>
</article-categories>
<title-group>
<article-title>Patients with oral tongue squamous cell carcinoma and co‑existing diabetes exhibit lower recurrence rates and improved survival: Implications for treatment</article-title>
</title-group>
<contrib-group>
<contrib contrib-type="author"><name><surname>Salehi</surname><given-names>Amir M.</given-names></name>
<xref rid="af1-ol-27-4-14275" ref-type="aff">1</xref></contrib>
<contrib contrib-type="author"><name><surname>Wang</surname><given-names>Lixiao</given-names></name>
<xref rid="af1-ol-27-4-14275" ref-type="aff">1</xref></contrib>
<contrib contrib-type="author"><name><surname>Gu</surname><given-names>Xiaolian</given-names></name>
<xref rid="af1-ol-27-4-14275" ref-type="aff">1</xref></contrib>
<contrib contrib-type="author"><name><surname>Coates</surname><given-names>Philip J.</given-names></name>
<xref rid="af2-ol-27-4-14275" ref-type="aff">2</xref></contrib>
<contrib contrib-type="author"><name><surname>Norberg Spaak</surname><given-names>Lena</given-names></name>
<xref rid="af1-ol-27-4-14275" ref-type="aff">1</xref></contrib>
<contrib contrib-type="author"><name><surname>Sgaramella</surname><given-names>Nicola</given-names></name>
<xref rid="af1-ol-27-4-14275" ref-type="aff">1</xref>
<xref rid="af3-ol-27-4-14275" ref-type="aff">3</xref></contrib>
<contrib contrib-type="author"><name><surname>Nylander</surname><given-names>Karin</given-names></name>
<xref rid="af1-ol-27-4-14275" ref-type="aff">1</xref>
<xref rid="c1-ol-27-4-14275" ref-type="corresp"/></contrib>
</contrib-group>
<aff id="af1-ol-27-4-14275"><label>1</label>Department of Medical Biosciences/Pathology, Ume&#x00E5; University, SE 901 85 Ume&#x00E5;, Sweden</aff>
<aff id="af2-ol-27-4-14275"><label>2</label>Research Centre for Applied Molecular Oncology, Masaryk Memorial Cancer Institute, Brno 656 53, Czech Republic</aff>
<aff id="af3-ol-27-4-14275"><label>3</label>Department of Oral and Maxillo-Facial Surgery, Mater Dei Hospital, I-70125 Bari, Italy</aff>
<author-notes>
<corresp id="c1-ol-27-4-14275"><italic>Correspondence to</italic>: Professor Karin Nylander, Department of Medical Biosciences/Pathology, Ume&#x00E5; University, Analysv&#x00E4;gen 9, SE 901 85 Ume&#x00E5;, Sweden, E-mail: <email>gaochang@hainmc.edu.cn karin.nylander@umu.se </email></corresp>
</author-notes>
<pub-date pub-type="collection">
<month>04</month>
<year>2024</year></pub-date>
<pub-date pub-type="epub">
<day>06</day>
<month>02</month>
<year>2024</year></pub-date>
<volume>27</volume>
<issue>4</issue>
<elocation-id>142</elocation-id>
<history>
<date date-type="received"><day>18</day><month>10</month><year>2023</year></date>
<date date-type="accepted"><day>17</day><month>01</month><year>2024</year></date>
</history>
<permissions>
<copyright-statement>Copyright: &#x00A9; Salehi et al.</copyright-statement>
<copyright-year>2024</copyright-year>
<license license-type="open-access">
<license-p>This is an open access article distributed under the terms of the <ext-link ext-link-type="uri" xlink:href="https://creativecommons.org/licenses/by-nc-nd/4.0/">Creative Commons Attribution-NonCommercial-NoDerivs License</ext-link>, which permits use and distribution in any medium, provided the original work is properly cited, the use is non-commercial and no modifications or adaptations are made.</license-p></license>
</permissions>
<abstract>
<p>Locoregional recurrences and distant metastases are major problems for patients with squamous cell carcinoma of the head and neck (SCCHN). Because SCCHN is a heterogeneous group of tumours with varying characteristics, the present study concentrated on the subgroup of squamous cell carcinoma of the oral tongue (SCCOT) to investigate the use of machine learning approaches to predict the risk of recurrence from routine clinical data available at diagnosis. The approach also identified the most important parameters that identify and classify recurrence risk. A total of 66 patients with SCCOT were included. Clinical data available at diagnosis were analysed using statistical analysis and machine learning approaches. Tumour recurrence was associated with T stage (P=0.001), radiological neck metastasis (P=0.010) and diabetes (P=0.003). A machine learning model based on the random forest algorithm and with attendant explainability was used. Whilst patients with diabetes were overrepresented in the SCCOT cohort, diabetics had lower recurrence rates (P=0.015 after adjusting for age and other clinical features) and an improved 2-year survival (P=0.025) compared with non-diabetics. Clinical, radiological and histological data available at diagnosis were used to establish a prognostic model for patients with SCCOT. Using machine learning to predict recurrence produced a classification model with 71.2&#x0025; accuracy. Notably, one of the findings of the feature importance rankings of the model was that diabetics exhibited less recurrence and improved survival compared with non-diabetics, even after accounting for the independent prognostic variables of tumour size and patient age at diagnosis. These data imply that the therapeutic manipulation of glucose levels used to treat diabetes may be useful for patients with SCCOT regardless of their diabetic status. Further studies are warranted to investigate the impact of diabetes in other SCCHN subtypes.</p>
</abstract>
<kwd-group>
<kwd>squamous cell carcinoma</kwd>
<kwd>tongue</kwd>
<kwd>recurrence</kwd>
<kwd>random forest</kwd>
<kwd>diabetes</kwd>
</kwd-group>
<funding-group>
<award-group>
<funding-source>Lion&#x0027;s Cancer Research Foundation, Ume&#x00E5; University, The Swedish Cancer Society</funding-source>
<award-id>23 2775 Pj 01H</award-id>
</award-group>
<award-group>
<funding-source>Ume&#x00E5; University, Region V&#x00E4;sterbotten, Ministry of Health Czech Republic</funding-source>
<award-id>00209805</award-id>
</award-group>
<award-group>
<funding-source>Czech Science Foundation</funding-source>
<award-id>GACR 21-13188S</award-id>
</award-group>
<funding-statement>The present study was supported by Lion&#x0027;s Cancer Research Foundation, Ume&#x00E5; University, The Swedish Cancer Society (contract number 23 2775 Pj 01H), Ume&#x00E5; University, Region V&#x00E4;sterbotten, Ministry of Health Czech Republic (MMCI, 00209805) and Czech Science Foundation (GACR 21-13188S).</funding-statement>
</funding-group>
</article-meta>
</front>
<body>
<sec sec-type="intro">
<title>Introduction</title>
<p>Squamous cell carcinoma of the head and neck (SCCHN) comprises tumours of different origin, including mucosa of the upper airways, the oral cavity and sinuses. Patients have a high mortality rate (<xref rid="b1-ol-27-4-14275" ref-type="bibr">1</xref>) and critical prognostic factors at diagnosis are tumour size and metastatic lymph nodes in the neck. A major problem for these patients is the high rate of tumour relapse, where locoregional recurrences develop in 30&#x2013;40&#x0025; of patients and distant metastases in 20&#x2013;30&#x0025; (<xref rid="b2-ol-27-4-14275" ref-type="bibr">2</xref>).</p>
<p>The best current predictive tool for SCCHN survival is the tumour-node-metastasis (TNM) staging system based on tumour morphology, without considering patient-specific factors such as age (<xref rid="b3-ol-27-4-14275" ref-type="bibr">3</xref>), sex and comorbidity (<xref rid="b4-ol-27-4-14275" ref-type="bibr">4</xref>). Immunohistochemistry and molecular genetics can also provide important information for prognosis and targeted therapy (<xref rid="b5-ol-27-4-14275" ref-type="bibr">5</xref>). However, molecular analyses are uncommon outside of research institutes and are not performed routinely in the clinical setting, highlighting the importance of analysing the prognostic impact of widely available clinicopathological factors that are easily accessible at the time of diagnosis. Diabetes, characterised by sustained hyperglycemia, represents one such factor, and is known to associate with an increased risk for many cancers including SCCHN, where higher levels of blood glucose and various lipids have been seen up to 30 years before diagnosis (<xref rid="b6-ol-27-4-14275" ref-type="bibr">6</xref>). Data from The Cancer Genome Atlas (TCGA) or other sources, including genomic, transcriptomic and clinical information have often been used to identify prognostic indicators in patients with SCCHN, often using computational algorithms and artificial intelligence (AI) approaches to produce lists of potential biomarkers, comprising differential expression of specific mRNAs, microRNAs, lncRNAs etc (<xref rid="b7-ol-27-4-14275" ref-type="bibr">7</xref>&#x2013;<xref rid="b11-ol-27-4-14275" ref-type="bibr">11</xref>). However, genomic and transcriptomic data are not commonly available in routine clinical practice, and patient management is therefore based on clinical, histological and radiological data. In addition, SCCHN is a heterogenous set of tumours that have different biologies and prognoses according to their site of origin, indicating that site-specific factors are involved in patient outcome (<xref rid="b12-ol-27-4-14275" ref-type="bibr">12</xref>).</p>
<p>Therefore, we focused on squamous cell carcinoma of the oral tongue (SCCOT), the most common subgroup of oral SCCHN, employing machine learning to investigate medical and clinicopathological data available at diagnosis and identify parameters that are important to predict recurrence in the routine clinical situation.</p>
</sec>
<sec sec-type="materials|methods">
<title>Materials and methods</title>
<sec>
<title/>
<sec>
<title>Material</title>
<p>The study was approved by the Regional Ethical Committee in Umea, Ume&#x00E5; University, Sweden (dnr 2014-193-32M), giving consent to achieve clinical information from the files from patients retrospectively and prospectively. Written informed consent was achieved from the patients after oral information given by ENT-staff. Medical records were retrieved for 139 patients with a verified diagnosis of SCCOT treated during 1997&#x2013;2019 at the University Hospital, Umea. Patients lacking clinical data, such as complete anamnestic information, or not having radiological data available, and/or not having diagnostic slides available for re-examination were excluded, leaving 66 patients that were included in the study. No tumour had positive M-stage and this factor was thus excluded from further analyses. In addition to the standard parameters used in TNM and histopathological classification, and known high-risk factors such as smoking status, we also retrieved information on common comorbidities such as allergies, cardiovascular problems and symptoms of metabolic syndrome. Patient data are summarised in <xref rid="tI-ol-27-4-14275" ref-type="table">Table I</xref>.</p>
</sec>
<sec>
<title>Worst pattern of invasion (WPOI) and Lymphocytic response (LR)</title>
<p>Tumours were also analysed for Worst Pattern of Invasion (WPOI) and Lymphocytic Response (LR) using haematoxylin/eosin stained slides. According to the evaluation scale of Brandwein-Gensler <italic>et al</italic> (<xref rid="b13-ol-27-4-14275" ref-type="bibr">13</xref>), WPOI scores range from 1&#x2013;5 (1=broad pushing tumour front, 2=pushing tumour fingers and separate tumour islands, 3=tumour islands comprising &#x003E;15 cells, 4=tumour islands comprising &#x003C;15 cells and 5=tumour satellites found at a distance of &#x2265;1 mm from the tumour). LR has a three grade-scale, where 1=continuous dense rim of lymphoid tissue, 2=patches of lymphoid tissue and 3=limited or no lymphocytic response (<xref rid="b13-ol-27-4-14275" ref-type="bibr">13</xref>).</p>
</sec>
<sec>
<title>Principal component analysis (PCA)</title>
<p>Soft independent modelling of class analogies (SIMCA) is a multivariate data analysis tool that identifies patterns and relationships between many variables simultaneously. We used SIMCA 16 (MKS data analytics solutions, Ume&#x00E5;, Sweden) with unsupervised principal component analysis (PCA) to identify clusters or trends in the clinical and histopathological parameters investigated.</p>
</sec>
<sec>
<title>Statistical analysis</title>
<p>Two-tailed Fisher exact tests were used to determine associations between different clinicopathological features, and Kaplan-Meier with log rank test was used for survival analysis. SPSS version 25 was used for calculations and P-values &#x003C;0.05 were considered statistically significant.</p>
</sec>
<sec>
<title>Random forest</title>
<p>We used the python library &#x2018;Lazy Predict&#x2019; (<uri xlink:href="https://lazypredict.readthedocs.io/en/latest">https://lazypredict.readthedocs.io/en/latest</uri>) for initial performance assessment of different machine learning models for our data. Random Forrest (RF) was identified as the best machine learning model for our data. The RF approach has the additional advantage of explainability by identifying the specific features that are principally responsible for prediction. RF is a machine learning algorithm based on randomly constructed decision trees using bootstrap aggregating to improve stability and accuracy (<xref rid="b14-ol-27-4-14275" ref-type="bibr">14</xref>). Thus, as well as identifying suitable features for classification, RF also ranks the relative importance of each variable in the classification scheme. The importance scores for features are calculated based on their contribution to the reduction of impurity in the decision trees that make up the forest. It allows RF to identify and rank features according to their predictive power. Features with higher importance scores are considered more significant in the model&#x0027;s decision-making process. The RF classification model and its features of importance were calculated using leave-one-out cross validation (LOOCV) (<xref rid="b15-ol-27-4-14275" ref-type="bibr">15</xref>).</p>
</sec>
</sec>
</sec>
<sec sec-type="results">
<title>Results</title>
<sec>
<title/>
<sec>
<title>Principal component analysis (PCA)</title>
<p>Unsupervised PCA was performed to get an overview of subject distributions based on clinical, radiological and histopathological factors available at diagnosis. However, no distinct clustering of patients with recurrence and those without was found (<xref rid="f1-ol-27-4-14275" ref-type="fig">Fig. 1</xref>).</p>
</sec>
<sec>
<title>Statistical analysis</title>
<p>Significant associations were seen between recurrence and T stage (P=0.001), radiological signs of neck metastasis (P=0.010) and diabetes (P=0.003) (<xref rid="tI-ol-27-4-14275" ref-type="table">Table I</xref>).</p>
</sec>
<sec>
<title>Random forest</title>
<p>The RF classifier was built from 14 clinical and histopathological features available at diagnosis for the 66 patients (listed in <xref rid="tII-ol-27-4-14275" ref-type="table">Table II</xref>). Performance was assessed by LOOCV and the optimized classification RF model (n_estimators=70, max_depth=10) achieved an accuracy of 71.2&#x0025; (ROC_AUC=0.729, sensitivity=0.583, specificity=0.786, balanced accuracy=0.685, F-score=0.595) for risk of recurrence. The three factors that were significantly associated with risk of recurrence in the statistical analysis-T-stage (high risk), radiological signs of neck metastasis (high risk), and diabetes (low risk)-were also among the five most important features in model building (<xref rid="f2-ol-27-4-14275" ref-type="fig">Fig. 2</xref>).</p>
</sec>
<sec>
<title>Features</title>
<p>That diabetic SCCOT patients showed a lower risk of recurrence than patients without diabetes was an unexpected result. More detailed investigation revealed that all diabetic patients were &#x003E;50 years old, compared to 57&#x0025; (31/54) of non-diabetics (P=0.005), and the majority of diabetics (9/12, 75&#x0025;) also had cardiovascular disease, compared to 22&#x0025; (12/54) of non-diabetics (P=0.001). Half of the patients with diabetes (6/12) showed a lymphocytic response (either as a continuous dense rim or as patches of lymphocytes), compared to 85&#x0025; (46/54) of patients without diabetes (P=0.014; <xref rid="tIII-ol-27-4-14275" ref-type="table">Table III</xref>). Of the 12 patients with diabetes, five were treated with metformin, four with insulin and three with diet only to control their hyperglycaemia. Information on T- and N-stage was not available for one diabetic patient, and the remaining 11 patients all had T1/T2 tumours, compared to 45/54 non-diabetics (P=0.204). None of the 11 diabetic patients with T1/T2 tumours had a recurrence, whereas 36&#x0025; (16/45) of non-diabetics with T1/T2 tumours had a recurrence (P=0.023). To reduce heterogeneity in clinicopathological features, we analysed the subgroup of non-diabetic patients over 50 years of age with a T1/T2 tumour, comparable to diabetic patients regarding age and T-stage. Kaplan-Meier analysis showed that diabetic patients had better 2-year overall survival than non-diabetics (P=0.025; <xref rid="f3-ol-27-4-14275" ref-type="fig">Fig. 3A</xref>). Of these patients, 42&#x0025; (10/24) non-diabetics developed recurrence, compared to none of the eleven in the diabetic group (P=0.015, Fisher&#x0027;s exact test). Longer-term follow up of these diabetic (<xref rid="b11-ol-27-4-14275" ref-type="bibr">11</xref>) and non-diabetic (<xref rid="b24-ol-27-4-14275" ref-type="bibr">24</xref>) patients using Kaplan-Meier analysis showed that diabetic patients had better recurrence-free survival than non-diabetics although this was not statistically significant (P=0.287; <xref rid="f3-ol-27-4-14275" ref-type="fig">Fig. 3B</xref>).</p>
</sec>
</sec>
</sec>
<sec sec-type="discussion">
<title>Discussion</title>
<p>Tumour recurrence is a major problem for SCCHN patients, and, with a local recurrence rate of 30&#x2013;40&#x0025; (<xref rid="b2-ol-27-4-14275" ref-type="bibr">2</xref>), there is an urgent need for tools to predict the risk of relapse to ensure appropriate treatment and patient monitoring. Many studies have used various approaches to improve the prognostic prediction for SCCHN patients, including the ability to estimate outcomes from clinical and genomic data, and AI and machine learning methods have been applied to large &#x2018;omic&#x2019; datasets and other data for this purpose (<xref rid="b16-ol-27-4-14275" ref-type="bibr">16</xref>&#x2013;<xref rid="b19-ol-27-4-14275" ref-type="bibr">19</xref>). Here, we investigated whether similar machine learning approaches using only clinically available data at diagnosis are useful for improving models of risk recurrence in SCCOT, the most common subgroup of SCCHN tumours. Using consecutive samples of SCCOT and data available from routine clinical investigations at diagnosis and medical histories, we identified that the machine learning model RF is a valuable approach, able to generate a model to predict SCCOT recurrence with an accuracy of 71.2&#x0025; using only these simple data.</p>
<p>Despite the relatively low performance of the overall model, unlike some AI approaches our modelling procedure provided information into the specific features responsible for prediction. Surprisingly, diabetes as a co-morbidity showed a strong positive influence on outcome; patients with diabetes had lower rates of recurrence than non-diabetic patients and a correspondingly better survival. According to the Swedish diabetes register, approximately half a million people have diabetes, and 85&#x2013;90&#x0025; of these have type II diabetes (<uri xlink:href="https://www.diabetes.se/diabetes">https://www.diabetes.se/diabetes</uri>). In our study, 18&#x0025; (12/66) of patients were diabetics (P&#x003C;0.001 compared to the general population) and eight had type II diabetes judged by their medication. Thus, our data are compatible with the general findings that diabetes is associated with an increased risk of cancer development, including SCCHN and the oral SCC subtype (<xref rid="b20-ol-27-4-14275" ref-type="bibr">20</xref>). Paradoxically, our data show that patients with diabetes have a decreased risk of recurrence.</p>
<p>Hyperglycaemia in diabetes is caused by improper function or reduced secretion of insulin from pancreas, and the correlation between diabetes and increased carcinogenesis risk is therefore thought to be due to hyperinsulinemia, hyperglycaemia and insulin resistance (<xref rid="b21-ol-27-4-14275" ref-type="bibr">21</xref>). Despite the association of hyperglycaemia with increased risk of developing cancer, none of the diabetic patients we studied showed tumour recurrence within the first 50 months of follow-up. The link between diabetes and lack of recurrence was retained when comparing the diabetic group, all of whom were over 50 years of age and with a T1/T2 tumour, to the group of non-diabetics who were also over 50 years of age and with a T1/T2 tumour, where 42&#x0025; of the non-diabetic patients showed a recurrence compared to none of the diabetic patients. This presents an apparent paradox, where hyperglycaemia associated with clinical diabetes is expected to cause an increased risk of cancer development, yet co-existing diabetes reduces the risk of cancer recurrence. The most plausible explanation for this discrepancy between expectation and reality is that patients diagnosed with diabetes receive one or more treatments and/or lifestyle changes to control their disease, and are regularly monitored in wealthy countries to prevent hyperglycaemia. Thus, advanced health care procedures ensure that diabetics show high hyperglycaemic levels only before their diagnosis, which is rapidly and effectively reduced by anti-diabetic therapy.</p>
<p>The majority of newly diagnosed diabetics are initially treated with Metformin as an anti-glycaemic treatment. Metformin directly inhibits tumour cell proliferation, including SCCHN cells (<xref rid="b21-ol-27-4-14275" ref-type="bibr">21</xref>) and has cytostatic effects when used therapeutically in non-diabetic women with operable breast cancer (<xref rid="b22-ol-27-4-14275" ref-type="bibr">22</xref>). Metformin users may also have a reduced risk of acquiring cancers such as colorectal, liver, lung, prostate and breast (<xref rid="b23-ol-27-4-14275" ref-type="bibr">23</xref>), although recent data suggest that this issue is controversial and remains to be proven (<xref rid="b24-ol-27-4-14275" ref-type="bibr">24</xref>). There is also evidence that the increased risk of recurrence of OSCC seen in type II diabetic patients is reduced in those who use Metformin (<xref rid="b25-ol-27-4-14275" ref-type="bibr">25</xref>). In this large retrospective study of more than 800 patients with oral SCC (OSCC), patients with type II diabetes showed worse survival. However, when taking Metformin treatment into account, survival improved significantly. Metformin has also shown a positive effect on histological grade of dysplasia in non-diabetics with oral premalignant lesions through its actions on mTOR signalling (<xref rid="b26-ol-27-4-14275" ref-type="bibr">26</xref>). Although these studies imply a specific effect of Metformin on inhibiting cancer formation and progression (<xref rid="b25-ol-27-4-14275" ref-type="bibr">25</xref>,<xref rid="b26-ol-27-4-14275" ref-type="bibr">26</xref>), only 42&#x0025; of diabetics in our cohort were treated with Metformin and the remaining diabetic patients were controlled with insulin (33&#x0025;) or dietary modification (25&#x0025;). As all diabetics were free of recurrence &#x003E;50 months of follow-up, the data indicate that not only Metformin but also other antiglycaemic treatments may have a positive impact on survival, in keeping with the lack of specific effects of Metformin versus other methods of control seen in other studies of Type II diabetic patients with SCCHN (<xref rid="b27-ol-27-4-14275" ref-type="bibr">27</xref>). That the improved overall survival of diabetic SCCOT patients was reduced after longer follow-up may be explained by the majority of diabetics (75&#x0025;) also suffering from cardiovascular disease as an additional comorbidity. The effect of controlling (reducing) circulating glucose levels on tumour growth is presumably linked to the extreme reliance of cancer cells on high glucose levels, where tumour cells require high levels of energy but use the inefficient process of aerobic glycolysis (the Warburg effect), which has been suggested as a therapeutic avenue for many cancers, irrespective of diabetes (<xref rid="b28-ol-27-4-14275" ref-type="bibr">28</xref>). The use of aerobic glycolysis by tumour cells is also important for DNA repair and helps to promote resistance to standard genotoxic therapeutic agents (<xref rid="b29-ol-27-4-14275" ref-type="bibr">29</xref>), which may also help to explain our observations of improved response in controlled diabetic patients. In addition to direct effects on tumour cell growth, diabetes also influences tumour associated altered immune responses. An inflammatory response has previously been shown to have a positive prognostic impact in SCCOT (<xref rid="b24-ol-27-4-14275" ref-type="bibr">24</xref>), and the majority of non-diabetics in our study (85&#x0025;) showed a higher LR than diabetics. That diabetics showed a lower frequency of CD3&#x002B; T-cells due to metabolic inhibition, lactic acidosis inhibiting T-cell viability and function (<xref rid="b30-ol-27-4-14275" ref-type="bibr">30</xref>) is in concordance with our results, where 50&#x0025; of diabetics showed limited or no LR.</p>
<p>In conclusion, we used clinical, radiological and histological data available in the routine care at diagnosis of patients with SCCOT to establish a prognostic model. Using machine learning to provide a risk of recurrence classification procedure produced a model with 71.2&#x0025; accuracy. An unexpected but important finding from feature importance was that none of the patients with diabetes showed tumour recurrence after &#x003E; 50 months follow-up. Although patients with diabetes are overrepresented among patients with SCCOT, diabetics showed less recurrence and improved survival compared to non-diabetics, even after accounting for the independent prognostic variables of tumour size and patient age at diagnosis. Even if the number of patients with diabetes and cardiovascular disease may seem a bit high in our study, 18.2 and 31.8&#x0025; respectively, there was no selection performed other than the availability of clinical, histological and radiological data.</p>
<p>Notwithstanding the limitations of our study in terms of cohort size, the major strength of the present study is the use of a single subtype of SCCHN, where data imply that reduction of glucose levels may be beneficial for all patients with SCCOT, not just patients undergoing treatment for their diabetes. In addition, irrespective of the genetic and clinical differences between SCCOT and other SCCHN tumours, our data also indicate that reduction of glucose levels may be useful for similar tumours in the head and neck region (larynx, jaw, thyroid, etc), which is an area for future investigations.</p>
</sec>
</body>
<back>
<ack>
<title>Acknowledgements</title>
<p>Not applicable.</p>
</ack>
<sec sec-type="data-availability">
<title>Availability of data and materials</title>
<p>The data generated in the present study are included in the figures and/or tables of this article.</p>
</sec>
<sec>
<title>Authors&#x0027; contributions</title>
<p>AMS, LW, PJC and KN designed the study. AMS and LW retrieved and analysed data. LNS, NS and XG participated in data analysis. AMS, LW, PJC and KN wrote the manuscript. AMS, LW, LNS, XG, NS, PJC and KN edited the manuscript. AMS and KN confirm the authenticity of all the raw data. All authors read and approved the final version of the manuscript.</p>
</sec>
<sec>
<title>Ethics approval and consent to participate</title>
<p>All procedures involving human participants were performed in accordance with the ethical standards of the institutional and/or national research committee and with the 1964 Helsinki Declaration and its later amendments. The present study was approved by the local ethics committee (Regionala Etikpr&#x00F6;vningsn&#x00E4;mnden, Ume&#x00E5; University, Ume&#x00E5;, Sweden; approval no. 2014-193-32M). Written informed consent was obtained from the patients after oral information given by Ear, Nose and Throat-staff.</p>
</sec>
<sec>
<title>Patient consent for publication</title>
<p>Not applicable.</p>
</sec>
<sec sec-type="COI-statement">
<title>Competing interests</title>
<p>The authors declare that they have no competing interests.</p>
</sec>
<ref-list>
<title>References</title>
<ref id="b1-ol-27-4-14275"><label>1</label><element-citation publication-type="journal"><person-group person-group-type="author"><name><surname>Shah</surname><given-names>JP</given-names></name><name><surname>Gil</surname><given-names>Z</given-names></name></person-group><article-title>Current concepts in management of oral cancer-surgery</article-title><source>Oral Oncol</source><volume>45</volume><fpage>394</fpage><lpage>401</lpage><year>2009</year><pub-id pub-id-type="doi">10.1016/j.oraloncology.2008.05.017</pub-id><pub-id pub-id-type="pmid">18674952</pub-id></element-citation></ref>
<ref id="b2-ol-27-4-14275"><label>2</label><element-citation publication-type="journal"><person-group person-group-type="author"><name><surname>Marur</surname><given-names>S</given-names></name><name><surname>Forastiere</surname><given-names>AA</given-names></name></person-group><article-title>Head and neck cancer: Changing epidemiology, diagnosis, and treatment</article-title><source>Mayo Clin Proc</source><volume>83</volume><fpage>489</fpage><lpage>501</lpage><year>2008</year><pub-id pub-id-type="doi">10.4065/83.4.489</pub-id><pub-id pub-id-type="pmid">18380996</pub-id></element-citation></ref>
<ref id="b3-ol-27-4-14275"><label>3</label><element-citation publication-type="journal"><person-group person-group-type="author"><name><surname>Lacy</surname><given-names>PD</given-names></name><name><surname>Piccirillo</surname><given-names>JF</given-names></name><name><surname>Merritt</surname><given-names>MG</given-names></name><name><surname>Zequeira</surname><given-names>MR</given-names></name></person-group><article-title>Head and neck squamous cell carcinoma: Better to be young</article-title><source>Otolaryngol Head Neck Surg</source><volume>122</volume><fpage>253</fpage><lpage>258</lpage><year>2000</year><pub-id pub-id-type="doi">10.1016/S0194-5998(00)70249-X</pub-id><pub-id pub-id-type="pmid">10652400</pub-id></element-citation></ref>
<ref id="b4-ol-27-4-14275"><label>4</label><element-citation publication-type="journal"><person-group person-group-type="author"><name><surname>B&#x00F8;je</surname><given-names>CR</given-names></name></person-group><article-title>Impact of comorbidity on treatment outcome in head and neck squamous cell carcinoma-a systematic review</article-title><source>Radiother Oncol</source><volume>110</volume><fpage>81</fpage><lpage>90</lpage><year>2014</year><pub-id pub-id-type="doi">10.1016/j.radonc.2013.07.005</pub-id><pub-id pub-id-type="pmid">23953753</pub-id></element-citation></ref>
<ref id="b5-ol-27-4-14275"><label>5</label><element-citation publication-type="journal"><person-group person-group-type="author"><name><surname>Bradford</surname><given-names>CR</given-names></name><name><surname>Ferlito</surname><given-names>A</given-names></name><name><surname>Devaney</surname><given-names>KO</given-names></name><name><surname>M&#x00E4;kitie</surname><given-names>AA</given-names></name><name><surname>Rinaldo</surname><given-names>A</given-names></name></person-group><article-title>Prognostic factors in laryngeal squamous cell carcinoma</article-title><source>Laryngoscope Investig Otolaryngol</source><volume>5</volume><fpage>74</fpage><lpage>81</lpage><year>2020</year><pub-id pub-id-type="doi">10.1002/lio2.353</pub-id><pub-id pub-id-type="pmid">32128433</pub-id></element-citation></ref>
<ref id="b6-ol-27-4-14275"><label>6</label><element-citation publication-type="journal"><person-group person-group-type="author"><name><surname>Huang</surname><given-names>Y</given-names></name><name><surname>Xiao</surname><given-names>X</given-names></name><name><surname>Sadeghi</surname><given-names>F</given-names></name><name><surname>Feychting</surname><given-names>M</given-names></name><name><surname>Hammar</surname><given-names>N</given-names></name><name><surname>Fang</surname><given-names>F</given-names></name><name><surname>Zhang</surname><given-names>Z</given-names></name><name><surname>Liu</surname><given-names>Q</given-names></name></person-group><article-title>Blood metabolic biomarkers and the risk of head and neck cancer: An epidemiological study in the Swedish AMORIS Cohort</article-title><source>Cancer Lett</source><volume>557</volume><fpage>216091</fpage><year>2023</year><pub-id pub-id-type="doi">10.1016/j.canlet.2023.216091</pub-id><pub-id pub-id-type="pmid">36764441</pub-id></element-citation></ref>
<ref id="b7-ol-27-4-14275"><label>7</label><element-citation publication-type="journal"><person-group person-group-type="author"><name><surname>Gu</surname><given-names>X</given-names></name><name><surname>Wang</surname><given-names>L</given-names></name><name><surname>Coates</surname><given-names>PJ</given-names></name><name><surname>Boldrup</surname><given-names>L</given-names></name><name><surname>Fahraeus</surname><given-names>R</given-names></name><name><surname>Wilms</surname><given-names>T</given-names></name><name><surname>Norberg-Spaak</surname><given-names>L</given-names></name><name><surname>Sgaramella</surname><given-names>N</given-names></name><name><surname>Nylander</surname><given-names>K</given-names></name></person-group><article-title>Transfer-RNA-derived fragments are potential prognostic factors in patients with squamous cell carcinoma of the head and neck</article-title><source>Genes (Basel)</source><volume>11</volume><fpage>1344</fpage><year>2020</year><pub-id pub-id-type="doi">10.3390/genes11111344</pub-id><pub-id pub-id-type="pmid">33202812</pub-id></element-citation></ref>
<ref id="b8-ol-27-4-14275"><label>8</label><element-citation publication-type="journal"><person-group person-group-type="author"><name><surname>Gu</surname><given-names>X</given-names></name><name><surname>Wang</surname><given-names>L</given-names></name><name><surname>Boldrup</surname><given-names>L</given-names></name><name><surname>Coates</surname><given-names>P</given-names></name><name><surname>Fahraeus</surname><given-names>R</given-names></name><name><surname>Sgaramella</surname><given-names>N</given-names></name><name><surname>Wilms</surname><given-names>T</given-names></name><name><surname>Nylander</surname><given-names>K</given-names></name></person-group><article-title>AP001056.1, A prognosis-related enhancer RNA in squamous cell carcinoma of the head and neck</article-title><source>Cancers (Basel)</source><volume>11</volume><fpage>347</fpage><year>2019</year><pub-id pub-id-type="doi">10.3390/cancers11030347</pub-id><pub-id pub-id-type="pmid">30862109</pub-id></element-citation></ref>
<ref id="b9-ol-27-4-14275"><label>9</label><element-citation publication-type="journal"><person-group person-group-type="author"><name><surname>Warner</surname><given-names>GC</given-names></name><name><surname>Reis</surname><given-names>PP</given-names></name><name><surname>Jurisica</surname><given-names>I</given-names></name><name><surname>Sultan</surname><given-names>M</given-names></name><name><surname>Arora</surname><given-names>S</given-names></name><name><surname>Macmillan</surname><given-names>C</given-names></name><name><surname>Makitie</surname><given-names>AA</given-names></name><name><surname>Gr&#x00E9;nman</surname><given-names>R</given-names></name><name><surname>Reid</surname><given-names>N</given-names></name><name><surname>Sukhai</surname><given-names>M</given-names></name><etal/></person-group><article-title>Molecular classification of oral cancer by cDNA microarrays identifies overexpressed genes correlated with nodal metastasis</article-title><source>Int J Cancer</source><volume>110</volume><fpage>857</fpage><lpage>868</lpage><year>2004</year><pub-id pub-id-type="doi">10.1002/ijc.20197</pub-id><pub-id pub-id-type="pmid">15170668</pub-id></element-citation></ref>
<ref id="b10-ol-27-4-14275"><label>10</label><element-citation publication-type="journal"><person-group person-group-type="author"><name><surname>Zhang</surname><given-names>F</given-names></name><name><surname>Liu</surname><given-names>Y</given-names></name><name><surname>Yang</surname><given-names>Y</given-names></name><name><surname>Yang</surname><given-names>K</given-names></name></person-group><article-title>Development and validation of a fourteen-innate immunity-related gene pairs signature for predicting prognosis head and neck squamous cell carcinoma</article-title><source>BMC Cancer</source><volume>20</volume><fpage>1015</fpage><year>2020</year><pub-id pub-id-type="doi">10.1186/s12885-020-07489-7</pub-id><pub-id pub-id-type="pmid">33081731</pub-id></element-citation></ref>
<ref id="b11-ol-27-4-14275"><label>11</label><element-citation publication-type="journal"><person-group person-group-type="author"><name><surname>Zhou</surname><given-names>RS</given-names></name><name><surname>Zhang</surname><given-names>EX</given-names></name><name><surname>Sun</surname><given-names>QF</given-names></name><name><surname>Ye</surname><given-names>ZJ</given-names></name><name><surname>Liu</surname><given-names>JW</given-names></name><name><surname>Zhou</surname><given-names>DH</given-names></name><name><surname>Tang</surname><given-names>Y</given-names></name></person-group><article-title>Integrated analysis of lncRNA-miRNA-mRNA ceRNA network in squamous cell carcinoma of tongue</article-title><source>BMC Cancer</source><volume>19</volume><fpage>779</fpage><year>2019</year><pub-id pub-id-type="doi">10.1186/s12885-019-5983-8</pub-id><pub-id pub-id-type="pmid">31391008</pub-id></element-citation></ref>
<ref id="b12-ol-27-4-14275"><label>12</label><element-citation publication-type="journal"><person-group person-group-type="author"><name><surname>Sgaramella</surname><given-names>N</given-names></name><name><surname>Gu</surname><given-names>X</given-names></name><name><surname>Boldrup</surname><given-names>L</given-names></name><name><surname>Coates</surname><given-names>PJ</given-names></name><name><surname>F&#x00E5;hraeus</surname><given-names>R</given-names></name><name><surname>Califano</surname><given-names>L</given-names></name><name><surname>Tartaro</surname><given-names>G</given-names></name><name><surname>Colella</surname><given-names>G</given-names></name><name><surname>Spaak</surname><given-names>LN</given-names></name><name><surname>Strom</surname><given-names>A</given-names></name><etal/></person-group><article-title>Searching for new targets and treatments in the battle against squamous cell carcinoma of the head and neck, with specific focus on tumours of the tongue</article-title><source>Curr Top Med Chem</source><volume>18</volume><fpage>214</fpage><lpage>218</lpage><year>2018</year><pub-id pub-id-type="doi">10.2174/1568026618666180116121624</pub-id><pub-id pub-id-type="pmid">29345578</pub-id></element-citation></ref>
<ref id="b13-ol-27-4-14275"><label>13</label><element-citation publication-type="journal"><person-group person-group-type="author"><name><surname>Brandwein-Gensler</surname><given-names>M</given-names></name><name><surname>Teixeira</surname><given-names>MS</given-names></name><name><surname>Lewis</surname><given-names>CM</given-names></name><name><surname>Lee</surname><given-names>B</given-names></name><name><surname>Rolnitzky</surname><given-names>L</given-names></name><name><surname>Hille</surname><given-names>JJ</given-names></name><name><surname>Genden</surname><given-names>E</given-names></name><name><surname>Urken</surname><given-names>ML</given-names></name><name><surname>Wang</surname><given-names>BY</given-names></name></person-group><article-title>Oral squamous cell carcinoma histologic risk assessment, but not margin status, is strongly predictive of local disease-free and overall survival</article-title><source>Am J Surg Pathol</source><volume>29</volume><fpage>167</fpage><lpage>178</lpage><year>2005</year><pub-id pub-id-type="doi">10.1097/01.pas.0000149687.90710.21</pub-id><pub-id pub-id-type="pmid">15644773</pub-id></element-citation></ref>
<ref id="b14-ol-27-4-14275"><label>14</label><element-citation publication-type="journal"><person-group person-group-type="author"><name><surname>Svetnik</surname><given-names>V</given-names></name><name><surname>Liaw</surname><given-names>A</given-names></name><name><surname>Tong</surname><given-names>C</given-names></name><name><surname>Culberson</surname><given-names>JC</given-names></name><name><surname>Sheridan</surname><given-names>RP</given-names></name><name><surname>Feuston</surname><given-names>BP</given-names></name></person-group><article-title>Random forest: A classification and regression tool for compound classification and QSAR modeling</article-title><source>J Chem Inf Comput Sci</source><volume>43</volume><fpage>1947</fpage><lpage>1958</lpage><year>2003</year><pub-id pub-id-type="doi">10.1021/ci034160g</pub-id><pub-id pub-id-type="pmid">14632445</pub-id></element-citation></ref>
<ref id="b15-ol-27-4-14275"><label>15</label><element-citation publication-type="journal"><person-group person-group-type="author"><name><surname>Pedregosa</surname><given-names>F</given-names></name><name><surname>Varoquaux</surname><given-names>G</given-names></name><name><surname>Gramfort</surname><given-names>A</given-names></name><name><surname>Michel</surname><given-names>V</given-names></name><name><surname>Thirion</surname><given-names>B</given-names></name><name><surname>Grisel</surname><given-names>O</given-names></name><name><surname>Blondel</surname><given-names>M</given-names></name><name><surname>Prettenhofer</surname><given-names>P</given-names></name><name><surname>Weiss</surname><given-names>R</given-names></name><name><surname>Dubourg</surname><given-names>V</given-names></name><etal/></person-group><article-title>Scikit-learn: Machine learning in python</article-title><source>J Mach Learn Res</source><volume>12</volume><fpage>2825</fpage><lpage>2830</lpage><year>2011</year></element-citation></ref>
<ref id="b16-ol-27-4-14275"><label>16</label><element-citation publication-type="journal"><person-group person-group-type="author"><name><surname>Alabi</surname><given-names>RO</given-names></name><name><surname>Elmusrati</surname><given-names>M</given-names></name><name><surname>Sawazaki-Calone</surname><given-names>I</given-names></name><name><surname>Kowalski</surname><given-names>LP</given-names></name><name><surname>Haglund</surname><given-names>C</given-names></name><name><surname>Coletta</surname><given-names>RD</given-names></name><name><surname>M&#x00E4;kitie</surname><given-names>AA</given-names></name><name><surname>Salo</surname><given-names>T</given-names></name><name><surname>Almangush</surname><given-names>A</given-names></name><name><surname>Leivo</surname><given-names>L</given-names></name></person-group><article-title>Comparison of supervised machine learning classification techniques in prediction of locoregional recurrences in early oral tongue cancer</article-title><source>Int J Med Inform</source><volume>136</volume><fpage>104068</fpage><year>2020</year><pub-id pub-id-type="doi">10.1016/j.ijmedinf.2019.104068</pub-id><pub-id pub-id-type="pmid">31923822</pub-id></element-citation></ref>
<ref id="b17-ol-27-4-14275"><label>17</label><element-citation publication-type="journal"><person-group person-group-type="author"><name><surname>Alabi</surname><given-names>RO</given-names></name><name><surname>Elmusrati</surname><given-names>M</given-names></name><name><surname>Leivo</surname><given-names>I</given-names></name><name><surname>Almangush</surname><given-names>A</given-names></name><name><surname>M&#x00E4;kitie</surname><given-names>AA</given-names></name></person-group><article-title>Machine learning explainability in nasopharyngeal cancer survival using LIME and SHAP</article-title><source>Sci Rep</source><volume>13</volume><fpage>8984</fpage><year>2023</year><pub-id pub-id-type="doi">10.1038/s41598-023-35795-0</pub-id><pub-id pub-id-type="pmid">37268685</pub-id></element-citation></ref>
<ref id="b18-ol-27-4-14275"><label>18</label><element-citation publication-type="journal"><person-group person-group-type="author"><name><surname>Alabi</surname><given-names>RO</given-names></name><name><surname>Almangush</surname><given-names>A</given-names></name><name><surname>Elmusrati</surname><given-names>M</given-names></name><name><surname>Leivo</surname><given-names>I</given-names></name><name><surname>M&#x00E4;kitie</surname><given-names>A</given-names></name></person-group><article-title>Measuring the usability and quality of explanations of a machine learning web-based tool for oral tongue cancer prognostication</article-title><source>Int J Environ Res Public Health</source><volume>19</volume><fpage>8366</fpage><year>2022</year><pub-id pub-id-type="doi">10.3390/ijerph19148366</pub-id><pub-id pub-id-type="pmid">35886221</pub-id></element-citation></ref>
<ref id="b19-ol-27-4-14275"><label>19</label><element-citation publication-type="journal"><person-group person-group-type="author"><name><surname>Alabi</surname><given-names>RO</given-names></name><name><surname>Almangush</surname><given-names>A</given-names></name><name><surname>Elmusrati</surname><given-names>M</given-names></name><name><surname>M&#x00E4;kitie</surname><given-names>AA</given-names></name></person-group><article-title>Deep machine learning for oral cancer: From precise diagnosis to precision medicine</article-title><source>Front Oral Health</source><volume>2</volume><fpage>794248</fpage><year>2022</year><pub-id pub-id-type="doi">10.3389/froh.2021.794248</pub-id><pub-id pub-id-type="pmid">35088057</pub-id></element-citation></ref>
<ref id="b20-ol-27-4-14275"><label>20</label><element-citation publication-type="journal"><person-group person-group-type="author"><name><surname>Giovannucci</surname><given-names>E</given-names></name><name><surname>Harlan</surname><given-names>DM</given-names></name><name><surname>Archer</surname><given-names>MC</given-names></name><name><surname>Bergenstal</surname><given-names>RM</given-names></name><name><surname>Gapstur</surname><given-names>SM</given-names></name><name><surname>Habel</surname><given-names>LA</given-names></name><name><surname>Pollak</surname><given-names>M</given-names></name><name><surname>Regensteiner</surname><given-names>JG</given-names></name><name><surname>Yee</surname><given-names>D</given-names></name></person-group><article-title>Diabetes and cancer, a consensus report</article-title><source>Diabetes Care</source><volume>33</volume><fpage>1674</fpage><lpage>1685</lpage><year>2010</year><pub-id pub-id-type="doi">10.2337/dc10-0666</pub-id><pub-id pub-id-type="pmid">20587728</pub-id></element-citation></ref>
<ref id="b21-ol-27-4-14275"><label>21</label><element-citation publication-type="journal"><person-group person-group-type="author"><name><surname>Wojciechowska</surname><given-names>J</given-names></name><name><surname>Krajewski</surname><given-names>W</given-names></name><name><surname>Bolanowski</surname><given-names>M</given-names></name><name><surname>Kr&#x0119;cicki</surname><given-names>T</given-names></name><name><surname>Zato&#x0144;ski</surname><given-names>T</given-names></name></person-group><article-title>Diabetes and cancer: A review of current knowledge</article-title><source>Exp Clin Endocrinol Diabetes</source><volume>124</volume><fpage>263</fpage><lpage>275</lpage><year>2016</year><pub-id pub-id-type="doi">10.1055/s-0042-100910</pub-id><pub-id pub-id-type="pmid">27219686</pub-id></element-citation></ref>
<ref id="b22-ol-27-4-14275"><label>22</label><element-citation publication-type="journal"><person-group person-group-type="author"><name><surname>Hadad</surname><given-names>SM</given-names></name><name><surname>Coates</surname><given-names>P</given-names></name><name><surname>Jordan</surname><given-names>LB</given-names></name><name><surname>Dowling</surname><given-names>RJ</given-names></name><name><surname>Chang</surname><given-names>MC</given-names></name><name><surname>Done</surname><given-names>SJ</given-names></name><name><surname>Purdie</surname><given-names>CA</given-names></name><name><surname>Goodwin</surname><given-names>PJ</given-names></name><name><surname>Stambolic</surname><given-names>V</given-names></name><name><surname>Moulder-Thompson</surname><given-names>S</given-names></name><etal/></person-group><article-title>Evidence for biological effects of metformin in operable breast cancer: Biomarker analysis in a pre-operative window of opportunity randomized trial</article-title><source>Breast Cancer Res Treat</source><volume>150</volume><fpage>149</fpage><lpage>155</lpage><year>2015</year><pub-id pub-id-type="doi">10.1007/s10549-015-3307-5</pub-id><pub-id pub-id-type="pmid">25682077</pub-id></element-citation></ref>
<ref id="b23-ol-27-4-14275"><label>23</label><element-citation publication-type="journal"><person-group person-group-type="author"><name><surname>Noto</surname><given-names>H</given-names></name><name><surname>Goto</surname><given-names>A</given-names></name><name><surname>Tsujimoto</surname><given-names>T</given-names></name><name><surname>Noda</surname><given-names>M</given-names></name></person-group><article-title>Cancer risk in diabetic patients treated with metformin: A systematic review and meta-analysis</article-title><source>PLoS One</source><volume>7</volume><fpage>e33411</fpage><year>2012</year><pub-id pub-id-type="doi">10.1371/journal.pone.0033411</pub-id><pub-id pub-id-type="pmid">22448244</pub-id></element-citation></ref>
<ref id="b24-ol-27-4-14275"><label>24</label><element-citation publication-type="journal"><person-group person-group-type="author"><name><surname>Dickerman</surname><given-names>BA</given-names></name><name><surname>Garc&#x00ED;a-Alb&#x00E9;niz</surname><given-names>X</given-names></name><name><surname>Logan</surname><given-names>RW</given-names></name><name><surname>Denaxas</surname><given-names>S</given-names></name><name><surname>Hern&#x00E1;n</surname><given-names>MA</given-names></name></person-group><article-title>Evaluating metformin strategies for cancer prevention: A target trial emulation using electronic health records</article-title><source>Epidemiology</source><volume>34</volume><fpage>690</fpage><lpage>699</lpage><year>2023</year><pub-id pub-id-type="doi">10.1097/EDE.0000000000001626</pub-id><pub-id pub-id-type="pmid">37227368</pub-id></element-citation></ref>
<ref id="b25-ol-27-4-14275"><label>25</label><element-citation publication-type="journal"><person-group person-group-type="author"><name><surname>Hu</surname><given-names>X</given-names></name><name><surname>Xiong</surname><given-names>H</given-names></name><name><surname>Chen</surname><given-names>W</given-names></name><name><surname>Huang</surname><given-names>L</given-names></name><name><surname>Mao</surname><given-names>T</given-names></name><name><surname>Yang</surname><given-names>L</given-names></name><name><surname>Wang</surname><given-names>C</given-names></name><name><surname>Huang</surname><given-names>D</given-names></name><name><surname>Wang</surname><given-names>Z</given-names></name><name><surname>Yu</surname><given-names>J</given-names></name><etal/></person-group><article-title>Metformin reduces the increased risk of oral squamous cell carcinoma recurrence in patients with type 2 diabetes mellitus: A cohort study with propensity score analyses</article-title><source>Surg Oncol</source><volume>35</volume><fpage>453</fpage><lpage>459</lpage><year>2020</year><pub-id pub-id-type="doi">10.1016/j.suronc.2020.09.023</pub-id><pub-id pub-id-type="pmid">33065527</pub-id></element-citation></ref>
<ref id="b26-ol-27-4-14275"><label>26</label><element-citation publication-type="journal"><person-group person-group-type="author"><name><surname>Gutkind</surname><given-names>JS</given-names></name><name><surname>Molinolo</surname><given-names>AA</given-names></name><name><surname>Wu</surname><given-names>X</given-names></name><name><surname>Wang</surname><given-names>Z</given-names></name><name><surname>Nachmanson</surname><given-names>D</given-names></name><name><surname>Harismendy</surname><given-names>O</given-names></name><name><surname>Alexandrov</surname><given-names>LB</given-names></name><name><surname>Wuertz</surname><given-names>BR</given-names></name><name><surname>Ondrey</surname><given-names>FG</given-names></name><name><surname>Laronde</surname><given-names>D</given-names></name><etal/></person-group><article-title>Inhibition of mTOR signaling and clinical activity of metformin in oral premalignant lesions</article-title><source>JCI Insight</source><volume>6</volume><fpage>e147096</fpage><year>2021</year><pub-id pub-id-type="doi">10.1172/jci.insight.147096</pub-id><pub-id pub-id-type="pmid">34255745</pub-id></element-citation></ref>
<ref id="b27-ol-27-4-14275"><label>27</label><element-citation publication-type="journal"><person-group person-group-type="author"><name><surname>Lee</surname><given-names>DJ</given-names></name><name><surname>McMullen</surname><given-names>CP</given-names></name><name><surname>Foreman</surname><given-names>A</given-names></name><name><surname>Huang</surname><given-names>SH</given-names></name><name><surname>Lu</surname><given-names>L</given-names></name><name><surname>Xu</surname><given-names>W</given-names></name><name><surname>de Almeida</surname><given-names>JR</given-names></name><name><surname>Liu</surname><given-names>G</given-names></name><name><surname>Bratman</surname><given-names>SV</given-names></name><name><surname>Goldstein</surname><given-names>DP</given-names></name></person-group><article-title>Impact of metformin on disease control and survival in patients with head and neck cancer: A retrospective cohort study</article-title><source>J Otolaryngol Head Neck Surg</source><volume>48</volume><fpage>34</fpage><year>2019</year><pub-id pub-id-type="doi">10.1186/s40463-019-0348-5</pub-id><pub-id pub-id-type="pmid">31345259</pub-id></element-citation></ref>
<ref id="b28-ol-27-4-14275"><label>28</label><element-citation publication-type="journal"><person-group person-group-type="author"><name><surname>Barrea</surname><given-names>L</given-names></name><name><surname>Caprio</surname><given-names>M</given-names></name><name><surname>Tuccinardi</surname><given-names>D</given-names></name><name><surname>Moriconi</surname><given-names>E</given-names></name><name><surname>Di Renzo</surname><given-names>L</given-names></name><name><surname>Muscogiuri</surname><given-names>G</given-names></name><name><surname>Colao</surname><given-names>A</given-names></name><name><surname>Savastano</surname><given-names>S</given-names></name></person-group><article-title>Could ketogenic diet &#x2018;starve&#x2019; cancer? Emerging evidence</article-title><source>Crit Rev Food Sci Nutr</source><volume>62</volume><fpage>1800</fpage><lpage>1821</lpage><year>2022</year><pub-id pub-id-type="doi">10.1080/10408398.2020.1847030</pub-id><pub-id pub-id-type="pmid">33274644</pub-id></element-citation></ref>
<ref id="b29-ol-27-4-14275"><label>29</label><element-citation publication-type="journal"><person-group person-group-type="author"><name><surname>Marcucci</surname><given-names>F</given-names></name><name><surname>Rumio</surname><given-names>C</given-names></name></person-group><article-title>Glycolysis-induced drug resistance in tumors-A response to danger signals?</article-title><source>Neoplasia</source><volume>23</volume><fpage>234</fpage><lpage>245</lpage><year>2021</year><pub-id pub-id-type="doi">10.1016/j.neo.2020.12.009</pub-id><pub-id pub-id-type="pmid">33418276</pub-id></element-citation></ref>
<ref id="b30-ol-27-4-14275"><label>30</label><element-citation publication-type="journal"><person-group person-group-type="author"><name><surname>Spanier</surname><given-names>G</given-names></name><name><surname>Ugele</surname><given-names>I</given-names></name><name><surname>Nieberle</surname><given-names>F</given-names></name><name><surname>Symeou</surname><given-names>L</given-names></name><name><surname>Schmidhofer</surname><given-names>S</given-names></name><name><surname>Brand</surname><given-names>A</given-names></name><name><surname>Meier</surname><given-names>J</given-names></name><name><surname>Spoerl</surname><given-names>S</given-names></name><name><surname>Krupar</surname><given-names>R</given-names></name><name><surname>R&#x00FC;mmele</surname><given-names>P</given-names></name><etal/></person-group><article-title>The predictive power of CD3<sup>&#x002B;</sup> T cell infiltration of oral squamous cell tumors is limited to non-diabetic patients</article-title><source>Cancer Lett</source><volume>499</volume><fpage>209</fpage><lpage>219</lpage><year>2021</year><pub-id pub-id-type="doi">10.1016/j.canlet.2020.11.029</pub-id><pub-id pub-id-type="pmid">33276040</pub-id></element-citation></ref>
<ref id="b31-ol-27-4-14275"><label>31</label><element-citation publication-type="journal"><person-group person-group-type="author"><name><surname>Lundqvist</surname><given-names>L</given-names></name><name><surname>Stenlund</surname><given-names>SH</given-names></name><name><surname>Laurell</surname><given-names>G</given-names></name><name><surname>Nylander</surname><given-names>K</given-names></name></person-group><article-title>The importance of stromal inflammation in squamous cell carcinoma of the tongue</article-title><source>J Oral Pathol Med</source><volume>41</volume><fpage>379</fpage><lpage>383</lpage><year>2012</year><pub-id pub-id-type="doi">10.1111/j.1600-0714.2011.01107.x</pub-id><pub-id pub-id-type="pmid">22084865</pub-id></element-citation></ref>
</ref-list>
</back>
<floats-group>
<fig id="f1-ol-27-4-14275" position="float">
<label>Figure 1.</label>
<caption><p>Principle component analysis of clinicopathological features at diagnosis in patients with squamous cell carcinoma of the oral tongue. Patients with recurrence are shown as red dots and patients without recurrence are shown as blue dots.</p></caption>
<graphic xlink:href="ol-27-04-14275-g00.tif"/>
</fig>
<fig id="f2-ol-27-4-14275" position="float">
<label>Figure 2.</label>
<caption><p>Clinical feature importance of the random forest model. T, tumour size; Hist_diff, histological differentiation; Radiol.s, radiological signs of neck metastasis; LR, lymphocytic response; WPOI, worst pattern of invasion; N, tumour spread to lymph node; Comb_treatment, combined treatment (surgery, irradiation and/or chemotherapy); CVD, cardiovascular disease.</p></caption>
<graphic xlink:href="ol-27-04-14275-g01.tif"/>
</fig>
<fig id="f3-ol-27-4-14275" position="float">
<label>Figure 3.</label>
<caption><p>Kaplan-Meier recurrence-free survival analysis of patients &#x003E;50 years old with a T1/T2 tumour, divided into patients with diabetes (red line) and without diabetes (blue line). (A) First 2 years follow-up (P=0.025). (B) Available follow-up time (P=0.287). Tick marks indicate censored cases.</p></caption>
<graphic xlink:href="ol-27-04-14275-g02.tif"/>
</fig>
<table-wrap id="tI-ol-27-4-14275" position="float">
<label>Table I.</label>
<caption><p>Clinicopathological features of patients with squamous cell carcinoma of the oral tongue (n=66).</p></caption>
<table frame="hsides" rules="groups">
<thead>
<tr>
<th align="left" valign="bottom">Clinicopathological features</th>
<th align="center" valign="bottom">No. (&#x0025;)</th>
</tr>
</thead>
<tbody>
<tr>
<td align="left" valign="top">Sex</td>
<td/>
</tr>
<tr>
<td align="left" valign="top">&#x00A0;&#x00A0;Female</td>
<td align="center" valign="top">31 (47.0)</td>
</tr>
<tr>
<td align="left" valign="top">&#x00A0;&#x00A0;Male</td>
<td align="center" valign="top">35 (53.0)</td>
</tr>
<tr>
<td align="left" valign="top">Age, years</td>
<td/>
</tr>
<tr>
<td align="left" valign="top">&#x00A0;&#x00A0;&#x2264;50</td>
<td align="center" valign="top">23 (34.8)</td>
</tr>
<tr>
<td align="left" valign="top">&#x00A0;&#x00A0;&#x003E;50</td>
<td align="center" valign="top">43 (65.2)</td>
</tr>
<tr>
<td align="left" valign="top">Localisation</td>
<td/>
</tr>
<tr>
<td align="left" valign="top">&#x00A0;&#x00A0;Oral tongue, unspecified</td>
<td align="center" valign="top">17 (25.8)</td>
</tr>
<tr>
<td align="left" valign="top">&#x00A0;&#x00A0;Lateral border</td>
<td align="center" valign="top">39 (59.1)</td>
</tr>
<tr>
<td align="left" valign="top">&#x00A0;&#x00A0;Tongue with overgrowth outside the oral tongue</td>
<td align="center" valign="top">10 (15.1)</td>
</tr>
<tr>
<td align="left" valign="top">T stage</td>
<td/>
</tr>
<tr>
<td align="left" valign="top">&#x00A0;&#x00A0;T1, T2</td>
<td align="center" valign="top">56 (85.0)</td>
</tr>
<tr>
<td align="left" valign="top">&#x00A0;&#x00A0;T3, T4</td>
<td align="center" valign="top">9 (13.6)</td>
</tr>
<tr>
<td align="left" valign="top">&#x00A0;&#x00A0;Missing</td>
<td align="center" valign="top">1 (1.5)</td>
</tr>
<tr>
<td align="left" valign="top">N stage</td>
<td/>
</tr>
<tr>
<td align="left" valign="top">&#x00A0;&#x00A0;N0</td>
<td align="center" valign="top">60 (90.9)</td>
</tr>
<tr>
<td align="left" valign="top">&#x00A0;&#x00A0;N1, N2</td>
<td align="center" valign="top">5 (7.6)</td>
</tr>
<tr>
<td align="left" valign="top">&#x00A0;&#x00A0;Missing</td>
<td align="center" valign="top">1 (1.5)</td>
</tr>
<tr>
<td align="left" valign="top">Radiology</td>
<td/>
</tr>
<tr>
<td align="left" valign="top">&#x00A0;&#x00A0;Neck metastasis</td>
<td align="center" valign="top">13 (19.7)</td>
</tr>
<tr>
<td align="left" valign="top">&#x00A0;&#x00A0;No neck metastasis</td>
<td align="center" valign="top">48 (72.7)</td>
</tr>
<tr>
<td align="left" valign="top">&#x00A0;&#x00A0;Reactive nodes</td>
<td align="center" valign="top">5 (7.6)</td>
</tr>
<tr>
<td align="left" valign="top">Degree of differentiation</td>
<td/>
</tr>
<tr>
<td align="left" valign="top">&#x00A0;&#x00A0;Poor</td>
<td align="center" valign="top">4 (6.1)</td>
</tr>
<tr>
<td align="left" valign="top">&#x00A0;&#x00A0;Poor-moderate</td>
<td align="center" valign="top">14 (21.2)</td>
</tr>
<tr>
<td align="left" valign="top">&#x00A0;&#x00A0;Moderate</td>
<td align="center" valign="top">19 (28.8)</td>
</tr>
<tr>
<td align="left" valign="top">&#x00A0;&#x00A0;Moderate-high</td>
<td align="center" valign="top">27 (40.9)</td>
</tr>
<tr>
<td align="left" valign="top">&#x00A0;&#x00A0;High</td>
<td align="center" valign="top">2 (3.0)</td>
</tr>
<tr>
<td align="left" valign="top">Worst pattern of invasion<sup><xref rid="tfn1-ol-27-4-14275" ref-type="table-fn">a</xref></sup></td>
<td/>
</tr>
<tr>
<td align="left" valign="top">&#x00A0;&#x00A0;Broad pushing fingers; separate tumour islands</td>
<td align="center" valign="top">1 (1.5)</td>
</tr>
<tr>
<td align="left" valign="top">&#x00A0;&#x00A0;Invasive islands (&#x003E;15 cells&#x2044;island)</td>
<td align="center" valign="top">10 (15.1)</td>
</tr>
<tr>
<td align="left" valign="top">&#x00A0;&#x00A0;Invasive islands (&#x003C;15 cells&#x2044;island), including single cell invasion</td>
<td align="center" valign="top">51 (77.3)</td>
</tr>
<tr>
<td align="left" valign="top">&#x00A0;&#x00A0;Tumour satellites with &#x2265;1 mm distance from tumour</td>
<td align="center" valign="top">4 (6.1)</td>
</tr>
<tr>
<td align="left" valign="top">Lymphocytic response<sup><xref rid="tfn1-ol-27-4-14275" ref-type="table-fn">a</xref></sup></td>
<td/>
</tr>
<tr>
<td align="left" valign="top">&#x00A0;&#x00A0;Continuous dense rim of lymphoid tissue</td>
<td align="center" valign="top">27 (40.9)</td>
</tr>
<tr>
<td align="left" valign="top">&#x00A0;&#x00A0;Patches of discontinuous dense</td>
<td align="center" valign="top">25 (37.9)</td>
</tr>
<tr>
<td align="left" valign="top">&#x00A0;&#x00A0;lymphoid infiltrate</td>
<td/>
</tr>
<tr>
<td align="left" valign="top">&#x00A0;&#x00A0;Limited or no response</td>
<td align="center" valign="top">14 (21.2)</td>
</tr>
<tr>
<td align="left" valign="top">Smoking</td>
<td/>
</tr>
<tr>
<td align="left" valign="top">&#x00A0;&#x00A0;Yes</td>
<td align="center" valign="top">37 (56.0)</td>
</tr>
<tr>
<td align="left" valign="top">&#x00A0;&#x00A0;No</td>
<td align="center" valign="top">25 (37.9)</td>
</tr>
<tr>
<td align="left" valign="top">&#x00A0;&#x00A0;Unknown</td>
<td align="center" valign="top">4 (6.1)</td>
</tr>
<tr>
<td align="left" valign="top">Diabetes</td>
<td/>
</tr>
<tr>
<td align="left" valign="top">&#x00A0;&#x00A0;Yes</td>
<td align="center" valign="top">12 (18.2)</td>
</tr>
<tr>
<td align="left" valign="top">&#x00A0;&#x00A0;No</td>
<td align="center" valign="top">54 (81.8)</td>
</tr>
<tr>
<td align="left" valign="top">Asthma</td>
<td/>
</tr>
<tr>
<td align="left" valign="top">&#x00A0;&#x00A0;Yes</td>
<td align="center" valign="top">8 (12.1)</td>
</tr>
<tr>
<td align="left" valign="top">&#x00A0;&#x00A0;No</td>
<td align="center" valign="top">58 (87.9)</td>
</tr>
<tr>
<td align="left" valign="top">Cardiovascular disease</td>
<td/>
</tr>
<tr>
<td align="left" valign="top">&#x00A0;&#x00A0;Yes</td>
<td align="center" valign="top">21 (31.8)</td>
</tr>
<tr>
<td align="left" valign="top">&#x00A0;&#x00A0;No</td>
<td align="center" valign="top">45 (68.2)</td>
</tr>
<tr>
<td align="left" valign="top">Combination treatment<sup><xref rid="tfn2-ol-27-4-14275" ref-type="table-fn">b</xref></sup></td>
<td/>
</tr>
<tr>
<td align="left" valign="top">&#x00A0;&#x00A0;Yes</td>
<td align="center" valign="top">50 (75.8)</td>
</tr>
<tr>
<td align="left" valign="top">&#x00A0;&#x00A0;No</td>
<td align="center" valign="top">16 (24.2)</td>
</tr>
<tr>
<td align="left" valign="top">Recurrence within 2 years</td>
<td/>
</tr>
<tr>
<td align="left" valign="top">&#x00A0;&#x00A0;Yes</td>
<td align="center" valign="top">24 (36.4)</td>
</tr>
<tr>
<td align="left" valign="top">&#x00A0;&#x00A0;No</td>
<td align="center" valign="top">42 (63.6)</td>
</tr>
<tr>
<td align="left" valign="top">Status</td>
<td/>
</tr>
<tr>
<td align="left" valign="top">&#x00A0;&#x00A0;Dead</td>
<td align="center" valign="top">26 (39.4)</td>
</tr>
<tr>
<td align="left" valign="top">&#x00A0;&#x00A0;Alive</td>
<td align="center" valign="top">40 (60.6)</td>
</tr>
</tbody>
</table>
<table-wrap-foot>
<fn id="tfn1-ol-27-4-14275"><label>a</label><p>Data previously reported for some patients (<xref rid="b31-ol-27-4-14275" ref-type="bibr">31</xref>).</p></fn>
<fn id="tfn2-ol-27-4-14275"><label>b</label><p>Combination of surgery, radiotherapy and/or chemotherapy.</p></fn>
</table-wrap-foot>
</table-wrap>
<table-wrap id="tII-ol-27-4-14275" position="float">
<label>Table II.</label>
<caption><p>Association between clinicopathological features and recurrence.</p></caption>
<table frame="hsides" rules="groups">
<thead>
<tr>
<th/>
<th align="center" valign="bottom" colspan="2">Recurrence</th>
<th/>
</tr>
<tr>
<th/>
<th align="center" valign="bottom" colspan="2"><hr/></th>
<th/>
</tr>
<tr>
<th align="left" valign="bottom">Clinicopathological features</th>
<th align="center" valign="bottom">Yes, n</th>
<th align="center" valign="bottom">No, n</th>
<th align="center" valign="bottom">P-value</th>
</tr>
</thead>
<tbody>
<tr>
<td align="left" valign="top">Sex</td>
<td/>
<td/>
<td/>
</tr>
<tr>
<td align="left" valign="top">&#x00A0;&#x00A0;Female</td>
<td align="center" valign="top">13</td>
<td align="center" valign="top">18</td>
<td align="center" valign="top">0.446</td>
</tr>
<tr>
<td align="left" valign="top">&#x00A0;&#x00A0;Male</td>
<td align="center" valign="top">11</td>
<td align="center" valign="top">24</td>
<td/>
</tr>
<tr>
<td align="left" valign="top">Age, years</td>
<td/>
<td/>
<td/>
</tr>
<tr>
<td align="left" valign="top">&#x00A0;&#x00A0;&#x2264;50</td>
<td align="center" valign="top">8</td>
<td align="center" valign="top">15</td>
<td align="center" valign="top">&#x003E;0.999</td>
</tr>
<tr>
<td align="left" valign="top">&#x00A0;&#x00A0;&#x003E;50</td>
<td align="center" valign="top">16</td>
<td align="center" valign="top">27</td>
<td/>
</tr>
<tr>
<td align="left" valign="top">Localisation</td>
<td/>
<td/>
<td/>
</tr>
<tr>
<td align="left" valign="top">&#x00A0;&#x00A0;Localized tumour on lateral border or unspecified</td>
<td align="center" valign="top">19</td>
<td align="center" valign="top">37</td>
<td align="center" valign="top">0.477</td>
</tr>
<tr>
<td align="left" valign="top">&#x00A0;&#x00A0;Overgrowth outside the oral tongue</td>
<td align="center" valign="top">5</td>
<td align="center" valign="top">5</td>
<td/>
</tr>
<tr>
<td align="left" valign="top">T stage<sup><xref rid="tfn3-ol-27-4-14275" ref-type="table-fn">a</xref></sup></td>
<td/>
<td/>
<td/>
</tr>
<tr>
<td align="left" valign="top">&#x00A0;&#x00A0;T1, T2</td>
<td align="center" valign="top">16</td>
<td align="center" valign="top">40</td>
<td align="center" valign="top">0.001</td>
</tr>
<tr>
<td align="left" valign="top">&#x00A0;&#x00A0;T3, T4</td>
<td align="center" valign="top">8</td>
<td align="center" valign="top">1</td>
<td/>
</tr>
<tr>
<td align="left" valign="top">N stage<sup><xref rid="tfn3-ol-27-4-14275" ref-type="table-fn">a</xref></sup></td>
<td/>
<td/>
<td/>
</tr>
<tr>
<td align="left" valign="top">&#x00A0;&#x00A0;N0</td>
<td align="center" valign="top">20</td>
<td align="center" valign="top">40</td>
<td align="center" valign="top">0.058</td>
</tr>
<tr>
<td align="left" valign="top">&#x00A0;&#x00A0;N1, N2</td>
<td align="center" valign="top">4</td>
<td align="center" valign="top">1</td>
<td/>
</tr>
<tr>
<td align="left" valign="top">Radiology</td>
<td/>
<td/>
<td/>
</tr>
<tr>
<td align="left" valign="top">&#x00A0;&#x00A0;Neck metastasis</td>
<td align="center" valign="top">9</td>
<td align="center" valign="top">4</td>
<td align="center" valign="top">0.010</td>
</tr>
<tr>
<td align="left" valign="top">&#x00A0;&#x00A0;No neck metastasis or reactive nodes</td>
<td align="center" valign="top">15</td>
<td align="center" valign="top">38</td>
<td/>
</tr>
<tr>
<td align="left" valign="top">Degree of differentiation</td>
<td/>
<td/>
<td/>
</tr>
<tr>
<td align="left" valign="top">&#x00A0;&#x00A0;Poorly, poorly-moderately or moderately differentiated</td>
<td align="center" valign="top">15</td>
<td align="center" valign="top">22</td>
<td align="center" valign="top">0.453</td>
</tr>
<tr>
<td align="left" valign="top">&#x00A0;&#x00A0;Moderately-well or well differentiated</td>
<td align="center" valign="top">9</td>
<td align="center" valign="top">20</td>
<td/>
</tr>
<tr>
<td align="left" valign="top">WPOI</td>
<td/>
<td/>
<td/>
</tr>
<tr>
<td align="left" valign="top">&#x00A0;&#x00A0;Broad pushing fingers; separate tumour islands or invasive islands (&#x003E;15 cells&#x2044;island)</td>
<td align="center" valign="top">2</td>
<td align="center" valign="top">9</td>
<td align="center" valign="top">0.303</td>
</tr>
<tr>
<td align="left" valign="top">&#x00A0;&#x00A0;Invasive islands (&#x003C;15 cells&#x2044;island) or tumour satellites with &#x2265;1 mm distance from tumour</td>
<td align="center" valign="top">22</td>
<td align="center" valign="top">33</td>
<td/>
</tr>
<tr>
<td align="left" valign="top">LR</td>
<td/>
<td/>
<td/>
</tr>
<tr>
<td align="left" valign="top">&#x00A0;&#x00A0;Continuous dense rim of lymphoid tissue or patches of discontinuous dense lymphoid infiltrate</td>
<td align="center" valign="top">22</td>
<td align="center" valign="top">30</td>
<td align="center" valign="top">0.066</td>
</tr>
<tr>
<td align="left" valign="top">&#x00A0;&#x00A0;Limited or no response</td>
<td align="center" valign="top">2</td>
<td align="center" valign="top">12</td>
<td/>
</tr>
<tr>
<td align="left" valign="top">Smoking<sup><xref rid="tfn4-ol-27-4-14275" ref-type="table-fn">b</xref></sup></td>
<td/>
<td/>
<td/>
</tr>
<tr>
<td align="left" valign="top">&#x00A0;&#x00A0;Yes</td>
<td align="center" valign="top">15</td>
<td align="center" valign="top">22</td>
<td align="center" valign="top">0.419</td>
</tr>
<tr>
<td align="left" valign="top">&#x00A0;&#x00A0;No</td>
<td align="center" valign="top">7</td>
<td align="center" valign="top">18</td>
<td/>
</tr>
<tr>
<td align="left" valign="top">Diabetes</td>
<td/>
<td/>
<td/>
</tr>
<tr>
<td align="left" valign="top">&#x00A0;&#x00A0;Yes</td>
<td align="center" valign="top">0</td>
<td align="center" valign="top">12</td>
<td align="center" valign="top">0.003</td>
</tr>
<tr>
<td align="left" valign="top">&#x00A0;&#x00A0;No</td>
<td align="center" valign="top">24</td>
<td align="center" valign="top">30</td>
<td/>
</tr>
<tr>
<td align="left" valign="top">Asthma</td>
<td/>
<td/>
<td/>
</tr>
<tr>
<td align="left" valign="top">&#x00A0;&#x00A0;Yes</td>
<td align="center" valign="top">3</td>
<td align="center" valign="top">5</td>
<td align="center" valign="top">&#x003E;0.999</td>
</tr>
<tr>
<td align="left" valign="top">&#x00A0;&#x00A0;No</td>
<td align="center" valign="top">21</td>
<td align="center" valign="top">37</td>
<td/>
</tr>
<tr>
<td align="left" valign="top">Cardiovascular disease</td>
<td/>
<td/>
<td/>
</tr>
<tr>
<td align="left" valign="top">&#x00A0;&#x00A0;Yes</td>
<td align="center" valign="top">6</td>
<td align="center" valign="top">15</td>
<td align="center" valign="top">0.422</td>
</tr>
<tr>
<td align="left" valign="top">&#x00A0;&#x00A0;No</td>
<td align="center" valign="top">18</td>
<td align="center" valign="top">27</td>
<td/>
</tr>
<tr>
<td align="left" valign="top">Combination treatment</td>
<td/>
<td/>
<td/>
</tr>
<tr>
<td align="left" valign="top">&#x00A0;&#x00A0;Yes</td>
<td align="center" valign="top">20</td>
<td align="center" valign="top">30</td>
<td align="center" valign="top">0.375</td>
</tr>
<tr>
<td align="left" valign="top">&#x00A0;&#x00A0;No</td>
<td align="center" valign="top">4</td>
<td align="center" valign="top">12</td>
<td/>
</tr>
</tbody>
</table>
<table-wrap-foot>
<fn id="tfn3-ol-27-4-14275"><label>a</label><p>Information about T and N stage was lacking for 1 patient.</p></fn>
<fn id="tfn4-ol-27-4-14275"><label>b</label><p>Information about smoking was lacking for 4 patients. WPOI, worst pattern of invasion; LR, lymphocytic response.</p></fn>
</table-wrap-foot>
</table-wrap>
<table-wrap id="tIII-ol-27-4-14275" position="float">
<label>Table III.</label>
<caption><p>Association between clinicopathological features and diabetes.</p></caption>
<table frame="hsides" rules="groups">
<thead>
<tr>
<th/>
<th align="center" valign="bottom" colspan="2">Diabetes</th>
<th/>
</tr>
<tr>
<th/>
<th align="center" valign="bottom" colspan="2"><hr/></th>
<th/>
</tr>
<tr>
<th align="left" valign="bottom">Clinicopathological features</th>
<th align="center" valign="bottom">Yes, n</th>
<th align="center" valign="bottom">No, n</th>
<th align="center" valign="bottom">P-value</th>
</tr>
</thead>
<tbody>
<tr>
<td align="left" valign="top">Sex</td>
<td/>
<td/>
<td/>
</tr>
<tr>
<td align="left" valign="top">&#x00A0;&#x00A0;Female</td>
<td align="center" valign="top">3</td>
<td align="center" valign="top">28</td>
<td align="center" valign="top">0.117</td>
</tr>
<tr>
<td align="left" valign="top">&#x00A0;&#x00A0;Male</td>
<td align="center" valign="top">9</td>
<td align="center" valign="top">26</td>
<td/>
</tr>
<tr>
<td align="left" valign="top">Age, years</td>
<td/>
<td/>
<td/>
</tr>
<tr>
<td align="left" valign="top">&#x00A0;&#x00A0;&#x2264;50</td>
<td align="center" valign="top">0</td>
<td align="center" valign="top">23</td>
<td align="center" valign="top">0.005</td>
</tr>
<tr>
<td align="left" valign="top">&#x00A0;&#x00A0;&#x003E;50</td>
<td align="center" valign="top">12</td>
<td align="center" valign="top">31</td>
<td/>
</tr>
<tr>
<td align="left" valign="top">Localisation</td>
<td/>
<td/>
<td/>
</tr>
<tr>
<td align="left" valign="top">&#x00A0;&#x00A0;Localised tumour on lateral border or unspecified</td>
<td align="center" valign="top">12</td>
<td align="center" valign="top">44</td>
<td align="center" valign="top">0.187</td>
</tr>
<tr>
<td align="left" valign="top">&#x00A0;&#x00A0;Overgrowth outside the oral tongue</td>
<td align="center" valign="top">0</td>
<td align="center" valign="top">10</td>
<td/>
</tr>
<tr>
<td align="left" valign="top">T stage<sup><xref rid="tfn5-ol-27-4-14275" ref-type="table-fn">a</xref></sup></td>
<td/>
<td/>
<td/>
</tr>
<tr>
<td align="left" valign="top">&#x00A0;&#x00A0;T1, T2</td>
<td align="center" valign="top">11</td>
<td align="center" valign="top">45</td>
<td align="center" valign="top">0.337</td>
</tr>
<tr>
<td align="left" valign="top">&#x00A0;&#x00A0;T3, T4</td>
<td align="center" valign="top">0</td>
<td align="center" valign="top">9</td>
<td/>
</tr>
<tr>
<td align="left" valign="top">N stage<sup><xref rid="tfn5-ol-27-4-14275" ref-type="table-fn">a</xref></sup></td>
<td/>
<td/>
<td/>
</tr>
<tr>
<td align="left" valign="top">&#x00A0;&#x00A0;N0</td>
<td align="center" valign="top">11</td>
<td align="center" valign="top">49</td>
<td align="center" valign="top">0.579</td>
</tr>
<tr>
<td align="left" valign="top">&#x00A0;&#x00A0;N1, N2</td>
<td align="center" valign="top">0</td>
<td align="center" valign="top">5</td>
<td/>
</tr>
<tr>
<td align="left" valign="top">Radiology</td>
<td/>
<td/>
<td/>
</tr>
<tr>
<td align="left" valign="top">&#x00A0;&#x00A0;Neck metastasis</td>
<td align="center" valign="top">1</td>
<td align="center" valign="top">12</td>
<td align="center" valign="top">0.434</td>
</tr>
<tr>
<td align="left" valign="top">&#x00A0;&#x00A0;No neck metastasis or reactive nodes</td>
<td align="center" valign="top">11</td>
<td align="center" valign="top">42</td>
<td/>
</tr>
<tr>
<td align="left" valign="top">Degree of differentiation</td>
<td/>
<td/>
<td/>
</tr>
<tr>
<td align="left" valign="top">&#x00A0;&#x00A0;Poorly, poor-moderate or moderately differentiated</td>
<td align="center" valign="top">5</td>
<td align="center" valign="top">32</td>
<td align="center" valign="top">0.341</td>
</tr>
<tr>
<td align="left" valign="top">&#x00A0;&#x00A0;Moderately-well or well differentiated</td>
<td align="center" valign="top">7</td>
<td align="center" valign="top">22</td>
<td/>
</tr>
<tr>
<td align="left" valign="top">WPOI</td>
<td/>
<td/>
<td/>
</tr>
<tr>
<td align="left" valign="top">&#x00A0;&#x00A0;Broad pushing fingers; separate tumour islands or invasive islands (&#x003E;15 cells&#x2044;island)</td>
<td align="center" valign="top">4</td>
<td align="center" valign="top">7</td>
<td align="center" valign="top">0.104</td>
</tr>
<tr>
<td align="left" valign="top">&#x00A0;&#x00A0;Invasive islands (&#x003C;15 cells&#x2044;island) or tumour satellites with &#x2265;1 mm distance from tumour</td>
<td align="center" valign="top">8</td>
<td align="center" valign="top">47</td>
<td/>
</tr>
<tr>
<td align="left" valign="top">LR</td>
<td/>
<td/>
<td/>
</tr>
<tr>
<td align="left" valign="top">&#x00A0;&#x00A0;Continuous dense rim of lymphoid tissue or patches of discontinuous dense lymphoid infiltrate</td>
<td align="center" valign="top">6</td>
<td align="center" valign="top">46</td>
<td align="center" valign="top">0.014</td>
</tr>
<tr>
<td align="left" valign="top">&#x00A0;&#x00A0;Limited or no response</td>
<td align="center" valign="top">6</td>
<td align="center" valign="top">8</td>
<td/>
</tr>
<tr>
<td align="left" valign="top">Smoking<sup><xref rid="tfn6-ol-27-4-14275" ref-type="table-fn">b</xref></sup></td>
<td/>
<td/>
<td/>
</tr>
<tr>
<td align="left" valign="top">&#x00A0;&#x00A0;Yes</td>
<td align="center" valign="top">8</td>
<td align="center" valign="top">29</td>
<td align="center" valign="top">0.501</td>
</tr>
<tr>
<td align="left" valign="top">&#x00A0;&#x00A0;No</td>
<td align="center" valign="top">3</td>
<td align="center" valign="top">22</td>
<td/>
</tr>
<tr>
<td align="left" valign="top">Asthma</td>
<td/>
<td/>
<td/>
</tr>
<tr>
<td align="left" valign="top">&#x00A0;&#x00A0;Yes</td>
<td align="center" valign="top">1</td>
<td align="center" valign="top">7</td>
<td align="center" valign="top">&#x003E;0.999</td>
</tr>
<tr>
<td align="left" valign="top">&#x00A0;&#x00A0;No</td>
<td align="center" valign="top">11</td>
<td align="center" valign="top">47</td>
<td/>
</tr>
<tr>
<td align="left" valign="top">Cardiovascular disease</td>
<td/>
<td/>
<td/>
</tr>
<tr>
<td align="left" valign="top">&#x00A0;&#x00A0;Yes</td>
<td align="center" valign="top">9</td>
<td align="center" valign="top">12</td>
<td align="center" valign="top">0.001</td>
</tr>
<tr>
<td align="left" valign="top">&#x00A0;&#x00A0;No</td>
<td align="center" valign="top">3</td>
<td align="center" valign="top">42</td>
<td/>
</tr>
<tr>
<td align="left" valign="top">Combination treatment</td>
<td/>
<td/>
<td/>
</tr>
<tr>
<td align="left" valign="top">&#x00A0;&#x00A0;Yes</td>
<td align="center" valign="top">8</td>
<td align="center" valign="top">42</td>
<td align="center" valign="top">0.465</td>
</tr>
<tr>
<td align="left" valign="top">&#x00A0;&#x00A0;No</td>
<td align="center" valign="top">4</td>
<td align="center" valign="top">12</td>
<td/>
</tr>
</tbody>
</table>
<table-wrap-foot>
<fn id="tfn5-ol-27-4-14275"><label>a</label><p>Information about T and N stage was lacking for 1 patient.</p></fn>
<fn id="tfn6-ol-27-4-14275"><label>b</label><p>Information about smoking was lacking for 4 patients. WPOI, worst pattern of invasion; LR, lymphocytic response.</p></fn>
</table-wrap-foot>
</table-wrap>
</floats-group>
</article>
