OL Oncology Letters 1792-1074 1792-1082 D.A. Spandidos 10.3892/ol.2022.13553 OL-24-06-13553 Articles Strong prognostic value of SLAMF7 protein expression in patients with lymph node-positive breast cancer AssidiMourad 1 2 Center of Excellence in Genomic Medicine Research, King Abdulaziz University, Jeddah 21589, Saudi Arabia Medical Laboratory Department, Faculty of Applied Medical Sciences, King Abdulaziz University, Jeddah 21589, Saudi Arabia Correspondence to: Dr Mourad Assidi, Center of Excellence in Genomic Medicine Research, King Abdulaziz University, PO BOX 80216, Jeddah 21589, Saudi Arabia, E-mail: mourad.assidi@gmail.com 12 2022 19 10 2022 24 6 433 28042022 03102022 Copyright: © Assidi et al. 2022 This is an open access article distributed under the terms of the Creative Commons Attribution-NonCommercial-NoDerivs License, 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.

Breast cancer (BC) in women is the second most commonly diagnosed type of cancer worldwide, and the leading cause of cancer-related mortality among women. To date, surgery is the main treatment option, often combined with other (neo)adjuvant therapeutic modalities to treat this malignancy and prevent relapse. Despite the invasive aspects of the majority of these therapeutic interventions and their associated side-effects, these treatments are still unable to effectively cure this disease and prevent relapse. Thus, there is an urgent need for the identification of more relevant biomarkers for more effective theranostics. Signaling lymphocytic activation molecule F7 (SLAMF7) is a glycosylated cell surface protein that plays a critical role in immune cell functions under both healthy conditions and in cancer. It is specifically targeted by elotuzumab for the treatment of multiple myeloma. The present retrospective study aimed to investigate the expression patterns of SLAMF7 and evaluate its associations with clinicopathological features, including the survival outcomes of patients with BC. The protein expression of SLAMF7 in BC was investigated in 278 lymph node-positive formalin-fixed and paraffin-embedded (FFPE) tissue blocks using tissue microarray and immunohistochemistry techniques. The results revealed a significant association between cytoplasmic SLAMF7 protein expression and several clinicopathological parameters, particularly age at diagnosis (P<0.007), tumor invasion (P<0.008) and vascular invasion (P=0.05). Kaplan-Meier analysis revealed that the overexpression of SLAMF7 was a strong positive prognosticator of both disease-free and disease-specific survival in the patients with BC (log-rank P=0.001 and P=0.008, respectively). This suggests that patients with SLAMF7 protein expression have a higher survival rate and a lower recurrence rate. On the whole, the present study demonstrated that a weak or no SLAMF7 expression was a powerful prognosticator of poor survival outcomes associated with both tumor and vascular invasion. Therefore, elotuzumab (as SLAMF7monoclonal antibody therapy) may be a promising option for targeted therapy worthy of clinical testing in patients with BC.

 signaling lymphocytic activation molecule F7 breast cancer tissue microarray immunohistochemistry prognosis lymph node survival Funding: No funding was received. Introduction

Female breast cancer (BC) is the second most diagnosed malignancy worldwide (1), accounting for over two million cases each year in the USA (2). It is also the cause of 1 in 6 deaths due to all cancer types (1). The incidence rate of BC is continually increasing by ~0.5% per year (3). According to the 2020 GLOBOCAN data, the age-standardized rates for both the incidence and mortality of BC in Saudi women were 28.8 and 8.4%, respectively (4). However, these rates continue to increase each year (3). Notably, the incidence numbers of BC in Saudi Arabia increased by 186% from 2004 to 2016 (5). It is considered that this steady increase in BC cases, particularly in Saudi Arabia, may be attributed to several factors related to lack of awareness, delayed diagnosis, aging populations and the unhealthy lifestyle choices related to low levels of physical activity, poor dietary habits and smoking (6,7).

To date, the main treatment modality implemented for patients with BC is surgery followed by chemotherapy, radiotherapy, hormonal therapy and/or immuno-/targeted therapy to prevent the recurrence of the disease (8). Despite the invasive aspects of the majority of these therapeutic interventions and their associated side effects, these treatments are still not sufficient to effectively cure this disease and prevent relapse. For instance, chemotherapy is a harmful procedure that has been shown to induce drug resistance in cancer cells. Moreover, hormonal therapy may lead to bone loss and thus, to frailty and fractures (9,10).

Several laudable studies have been performed to investigate BC and identify potential biomarkers. Only a few of these therapeutic targets have already been studied in clinical trials to evaluate the response to treatment and disease progression, such as estrogen receptor (ER) (11), progesterone receptor (PR) (12), human epidermal growth factor receptor 2 (HER2) (13), nuclear protein Ki67 (Ki67) (14), urokinase-type plasminogen activator (15), tumor protein p53 (p53) (16), cyclin E (17) and neuropeptide substance P (18). Recent developments in cancer immunotherapy hold promise as possible treatment options for a variety of cancer types, including BC (19). For instance, programmed death-ligand 1 was the first immune checkpoint blockade drug approved by the US Food and Drug Administration (FDA) for the treatment of patients with triple-negative metastatic BC in 2019 (20). Other types of immunotherapies are currently available, including checkpoint blockade, adoptive cellular therapy and cancer vaccinology (21). Thus far, targeted anticancer therapies are not yet able to cure BC as single agents, which entails their combination with chemotherapy and/or radiotherapy to obtain improved survival outcomes. Furthermore, they were unable to provide reduced cytotoxicity on non-target tissues and to eradicate the cancer stem cells in the tumor mass (22,23). These hurdles to deliver effective and personalized BC therapeutics can be explained by the molecular pathophysiology of this aggressive tumor that remains poorly understood.

BC is a heterogeneous disease with several clinical subtypes, cancer stem cells niches, molecular signatures and oncologic signaling pathways. This complexity is further amplified by additional contributing factors, including late-stage detection, an intricate network of crosstalks and signaling pathways, drug resistance and a higher recurrence of the disease. These challenges combined with the heavy burden of this malignancy on patients, their families and the healthcare system, are urging scientists to perform research focusing on the identification of effective diagnostic biomarkers that may pave the way towards better theranostics. In this context, signaling lymphocytic activation molecule F7 (SLAMF7; previously known as CS1, CD2 subset1, CRACC and CD319) is a glycosylated cell surface protein that has been found to play a critical role in immune cell functions (24). This transmembrane receptor is located on the long arm of chromosome 1 (1q23.3) and is a member of the signaling lymphocyte activation molecule SLAM family (25). Studies have indicated that SLAMF7 has a unique pattern that is ubiquitously expressed in several cancer types, while its expression in normal cells is restricted to selected immune cell types, mainly natural killer (NK) cells and mature dendritic cells, but not on normal hematopoietic stem cells or other lymphocytes/normal tissues (24,26,27). These properties have made SLAMF7 a promising therapeutic target given its ability to activate NK cells specifically in tumor cells and boost their immunogenic cell death (phagocytosis, apoptosis, immune cells activation, cell signaling and gene expression), particularly when triggered by an antibody or a natural ligand (28–30). This SLAMF7-driven interaction has been shown to result in an increase in NK cytotoxicity, macrophage super activation and an inflammatory cytokine storm in rheumatoid arthritis (31,32). Of note, the monoclonal antibody, elotuzumab, has been demonstrated to specifically target SLAMF7, which is abundantly expressed on multiple myeloma (MM) cells. It has been shown to attract NK cells and to exert anticancer effects via antibody-dependent cell-mediated cytotoxicity (ADCC) in MM cells (26,33,34).

In solid tumors, SLAMF7 has recently been shown to be expressed in colorectal cancer cells (35–37), ovarian and cervical cancers (38,39), as well as in liver cancer cell lines (40) and multiple murine cancer models (41). The promise of SLAMF7 as an immunotherapeutic target with possible clinical outcomes in patients with various types of tumors has rendered it the focus of several studies (as aforementioned).

To the best of our knowledge, the present study is the first to investigate the expression of SLAMF7 in BC. This study aimed to assess the protein expression levels of SLAMF7 and its correlation with clinicopathological features of BC patients to evaluate its potential value as a prognosticator of BC.

 Patients and methods <sec> <title>Patient series

The present retrospective study included 278 lymph node-positive cases from 730 formalin-fixed and paraffin-embedded (FFPE) blocks of primary BC samples retrieved from the Pathology Department, King Abdulaziz University, Jeddah, Saudi Arabia covering the period from January 1995 to December 2014. The inclusion criteria included all available primary BC FFPE tissues collected from consenting patients who had full annotated clinicopathological data, regardless of their associated systemic diseases status. Only primary BC cases with unavailable FFPE sample and/or annotation data were excluded. FFPE blocks were processed routinely with hematoxylin and eosin for the evaluation of histopathological features, histological grading and the TNM-based staging of the tumor. The patient clinicopathological parameters were obtained from their medical records and are summarized in Table I.

 Treatment and follow-up

All (100%) consenting patients with BC were subjected to surgery, i.e., lumpectomy, radical or modified radical mastectomy with axillary clearance. Post-operative early adjuvant systemic therapy in the form of chemotherapy, radiotherapy and hormonal therapy was administered to 77, 60 and 25% of the patients, respectively. Following treatment, the patients were observed at 6–12-month intervals until mortality or the end of the follow-up period in June, 2016 (date of data collection). The mean follow-up time for the whole series was 37 months (range, 1–252 months). During the follow-up, patients were subjected to repeated clinical examinations and bone isotope scan, chest and abdominal-pelvic CAT scans were performed whenever needed. In most instances, the causes of death were obvious on clinical grounds alone. The autopsy was not performed in any case.

 Tissue microarray (TMA) and immunohistochemistry (IHC)

A total of 730 BC FFPE blocks were used to construct a TMA as previously described (42). TMA slides were utilized for the evaluation of SLAMF7 expression pattern using IHC with anti-SLAMF7/CS1 primary antibody (1:100 dilution; cat. no. ab202840, Abcam). Anti-SLAMF7 primary antibody was applied manually. Staining and processing were performed as previously described (43). Briefly, a fully automated protocol was designed to include deparaffinization with EZ Prep (Ventana Medical Systems, Inc.; Roche Diagnostics) at 75°C and incubation with the anti-SLAMF7/CS1 primary antibody for 1 h at 37°C. Staining and processing were thereafter performed with the ready-to-use iView DAB Detection kit (Ventana Medical Systems, Inc.; Roche Diagnostics) which contains a pre-diluted secondary antibody solution that is processed by the automated staining system (Ventana Medical Systems, Inc.; Roche Diagnostics) Ventana BenchMark XT for 1 h at 37°C. Counterstaining was performed using hematoxylin II (Ventana Medical Systems, Inc.; Roche Diagnostics) at room temperature for 4 min and Bluing Reagent (Ventana Medical Systems, Inc.; Roche Diagnostics) for 4 min. The stained TMA slides were washed with water and mild detergent followed by 3 min of several successive immersions into alcohol buffer at increasing concentrations (70, 95 and 100%). Tissue-Tek glass mounting medium was applied to each slide and covered with a glass coverslip.

 Evaluation of SLAMF7 staining intensity

The expression of SLAMF7 in the tumor tissue was assessed in a manner blinded to the clinical data using a Nikon light microscope (Model no. 6132, Nikon Corporation) at a magnification of ×40. The tumor cells which exhibited cytoplasmic staining were graded into four categories as follows: 0, Negative, no detectable staining; 1+, weak, yet detectable staining; 2+, moderate, clearly positive yet still weak; 3+, heavy staining, intense. As previously described (44,45), the cytoplasmic index score was calculated where both the intensity of the staining and the fraction of positively stained cells were taken into account using the following formula: I=0 × f0 + 1 × f1 + 2 × f2 + 3 × f3, where (I) is the staining index and (f0-f3) are the fractions of the cells showing a defined level of staining intensity (from 0 to +3). Theoretically, the index scores could vary between 0 and 300. The expression patterns were imaged and digitized using a Coolsnap Pro Color camera and ImagePro® Plus software (Media Cybernetics, Inc.).

 Statistical analysis

Fischer's exact test was used to assess the significance of the association between different categorical variables. Univariate survival analysis for the outcome measure [disease-specific survival (DSS) and disease-free survival (DFS)] was based on the Kaplan-Meier method, with the log-rank (Mantel-Cox) comparison test. Additionally, Cox regression multivariate analysis was performed to assess the possible independent prognostic impact of SLAMF7 protein expression in relation to the age, lymph node status, tumor grade and histological type of the patients. In all tests, a value of P<0.05 was considered to indicate a statistically significant difference. SPSS® (IBM Corp.) software packages (PASW Statistics for Windows, version 19) were used to perform all statistical analyses.

 In silico analysis of SLAMF7 mRNA expression

To further validate the findings of the present retrospective study that assessed the SLAMF protein expression in BC, transcription data from The Cancer Genome Atlas (TCGA) were analyzed using the freely available web application, The University of ALabama at Birmingham CANcer data analysis Portal (UALCAN; available at: http://ualcan.path.uab.edu/analysis.html) (46) and the online multi-omic exploration tool of the University of California, Santa Cruz (UCSC Xena; available at: http://xena.ucsc.edu/#overview) (47). Using the TCGA data repository, which is a comprehensive, user-friendly and interactive web resource allowing graphical and statistical analyses of cancer OMICS data, SLAMF7 mRNA expression in BC was then analyzed and compared with normal breast tissues as a control (available from the same platform) using Student's t-test (P<0.05 was considered to indicate a statistically significant difference).

 Results <sec> <title>Expression profile of SLAMF7 in primary BC samples

The results revealed that the cellular localization of SLMAF7 protein expression was mainly cytoplasmic in the primary BC samples, as well as in the lymph node-positive cases. It was found that ~20% of the primary samples exhibited moderate/strong (high) expression patterns, while the majority of the samples (80%) had either negative or weak (low) expression profiles (Fig. 1A-E). On the other hand, ~70% of the cancerous tissues in the lymph node-positive samples exhibited a high cytoplasmic expression (2+, 3+) while 30% of the samples exhibited low cytoplasmic expression patterns (0, 1+) (data not shown). The cytoplasmic expression patterns of 278 lymph node-positive primary BC cases are illustrated in Fig. 1. Of note, a perinuclear-like staining was observed. However, it was uncommon and difficult to confirm.

 Association of SLAMF7 protein expression patterns with clinicopathological features

The association of cytoplasmic SLAMF7 protein expression in lymph node-positive BC with the patient clinicopathological characteristics using different cut-off values revealed that the cut-off value for low (0, 1+) SLAMF7 protein expression compared to high (2+, 3+) SLAMF7 protein expression (low expression vs. high expression) was the strongest discriminator. Based on the aforementioned discriminator, the results revealed that there were significant associations between the cytoplasmic SLAMF7 protein expression profile and the age of the patients at diagnosis, in that the proportion of primary BC tissues with higher SLAMF7 protein expression was greater in younger patients (<50 years; 27%) compared with that in older patients (>50 years; 13%) (P<0.007; Table I). In addition, a significant association was found between the SLAMF7 expression profile and tumor invasion. BC tissues with a high invasive characteristic had a lower SLAMF7 protein expression than less invasive tumors (P<0.008; Table I).

The same tendency was observed between the SLAMF7 protein expression patterns and vascular invasion. Indeed, tumors with highly vascular invasive cells exhibited a lower SLAMF7 expression pattern than those with low vascular invasion (P=0.05). However, the other clinicopathological features did not exhibit any significant associations with the SLAMF7 protein expression profiles, including the hormonal and HER2 protein status (P=0.9 and P=0.2, respectively), as well as tumor grade (P=0.8), tumor margin (P=0.7) and tumor size (P=0.2) (Table I).

 Association of SLAMF7 protein expression patterns with survival outcomes

In Kaplan-Meier analysis, the tier two cut-off [no expression (0) vs. expression (1+, 2+ and 3+)] was the strongest discriminator. Using this cut-off, survival analysis revealed that patients with BC with positive SLAMF7 protein expression patterns in their lymph node positive tissues (1+, 2+ and 3+) had a lower relapse rate (DFS) than those without SLAMF7 expression profiles. For example, after 5 years of follow-up, all patients with lymph node-positive BC without SLAMF7 expression (100%) exhibited disease recurrence, compared with a recurrence rate of only 40% in the lymph nodes of with BC with a positive SLAMF7 protein expression (P<0.001, log-rank; Fig. 2).

The assessment of DSS using the same cut-off points [negative (0) vs. positive (1+, 2+ and 3+)] also revealed a significant association. In fact, patients with lymph node-positive BC positive for SLAMF7 protein expression survived for a longer period of time. After 5 years of follow-up, ~30% of patients with BC with lymph node-positive tumors with a positive SLAMF7 expression died compared to a 100% death rate in those without a SLAMF7 expression pattern (P<0.008, log-rank; Fig. 3).

Multivariate Cox regression analysis revealed that the SLAMF7 expression profile (low, 0 and 1+; vs. high, 2+ and 3+) was not an independent factor for a poor DFS and DSS in relation to patient age, lymph node status, tumor grade and vascular invasion (Table II).

 SLAMF7 mRNA expression

The in silico analysis of SLAMF7 mRNA expression available in the freely available UCSC Xena or UALCAN transcriptomic databases confirmed that the SLAMF7 transcript was expressed in the breast invasive carcinoma cohort. Using the Student's t-test, the expression of this mRNA was shown to be higher than that in normal breast tissues according to the UALCAN database (P<0.001; Fig. 4).

An overview of the main molecular, cellular and signaling functions of SLAMF7 as regards its role in the immune system, as well as in other tissues is presented in Fig. 5.

 Discussion

BC remains a major health concern and a very common cause of cancer-related mortality among women worldwide, with an inherent complexity and molecular heterogeneity (48,49). Moreover, the current treatment modalities for BC are based on histopathological features, such as age, stage, grade, tumor size and receptor status (50). However, patients with BC with similar conditions and diagnoses may have different prognoses, responses to treatment and disease courses when treated with the same therapeutic regimen. This inherent complexity is due to different morphological, pathophysiological, clinical and environmental characteristics (51). In the post-genomic era, great efforts have been made to overcome this heterogeneity of BC and to further elucidate this complexity. In addition to ER, PR and HER2 receptors, other promising biomarkers have been proposed to further elucidate the molecular heterogeneity of BC (52). Since the majority of tumors are no longer considered as a single disease with predefined molecular features, the identification of more relevant clinical and molecular features of BC is urgently required in order to identify therapeutic targets and define pathways of disease progression leading to an earlier diagnosis, better prognosis and more precise therapeutics (53).

Multiomics approaches have led to substantial progress being made in the accurate molecular stratification of BC into different subtypes to identify more appropriate/precise therapeutic options (54–56). However, much still remains to be done before precision theranostics for BC can be achieved, and thus more molecular biomarkers are required for this aggressive disease.

In this context, SLAMF7 is expressed in selected immune cells and functions as an inhibitor in monocytes to modulate pro-inflammatory immune responses (57). Chen et al (30) recently discovered that SLAMF7 is required for the phagocytosis of hematopoietic malignancy cells, which is crucial for cancer treatment. Notably, elotuzumab is the targeted drug that specifically targets SLAMF7 in patients with myeloma via ADCC (26,33,34).

Although SLAMF7 has been reported to be rarely expressed in normal tissues, it is expressed in certain types of cancer, such as colorectal cancer and multiple myeloma (26,58). In addition, analysis of data from TCGA has demonstrated that SLAMF7 is also expressed in certain solid tumors at either the RNA and/or protein level (59–61); however, no specific study has yet been conducted using BC tissue, at least to the best of our knowledge. In addition, it is considered that the availability of an approved anti-SLAMF7 monoclonal antibody (elotuzumab) would be an advantage that would not only increase the value of studies on patients with BC, but would also be beneficial for oncologists, pathologists and cancer researchers.

To the best of our knowledge, this is the first study to investigate the expression patterns of SLAMF7 in BC tissue and to demonstrate its potential prognostic value in BC. The results of the present study confirmed the presence of SLAMF7 protein in BC tissues. Indeed, SLAMF7 was strongly expressed in the cytoplasm of BC tissue. Of note, it was more overexpressed in the samples from patients with BC with a positive lymph node status (advanced stages) than in those with only primary BC. Moreover, the cytoplasmic expression of SLAMF7 was significantly associated with several clinicopathological characteristics in the present cohort, including age (P<0.007), tumor invasion (P<0.008) and vascular invasion (P=0.05). The results of the present study clearly demonstrated that a low expression of SLAMF7 protein was associated with more aggressive and invasive BC cases. In fact, the low expression of SLAMF7 was found in 81 and 86% of patients with BC with positive tumor invasion and positive vascular invasion, respectively (Table I).

Several studies among Saudi women have reported that the majority were diagnosed with BC at <50 years of age (62–65). These findings were also confirmed in the present study cohort, in which >51% of the patients with BC were <50 years of age when they were diagnosed with BC. However, in the USA, the SEER cancer statistics review reported that the median age of American women at the time of diagnosis of BC was 62 years (66). These results indicate that the onset of BC is delayed by >10 years in the USA as compared to Saudi women. This significant early-onset of BC among Saudi women may be due to a number of factors, including population ageing, economic and social disparities, lifestyle choices and environmental factors (62,67). Of note, the results of the present study demonstrated that the expression of SLAMF7 was higher in younger patients with BC than in their older counterparts, which may be attributed to, at least in part, the lower activity of immune cells in the elderly (68).

Using Kaplan-Meier analysis, significant associations were found between SLAMF7 expression in BC and both DFS and DSS (P<0.001 and P<0.008; log-rank test, respectively). The results revealed that patients with BC who overexpressed SLAMF7 had better survival outcomes with longer survival and lower recurrence rates. In fact, all (100%) the patients with BC without SLAMF7 expression had disease recurrence after 5 years of follow-up, whereas only 35% of patients with a positive expression of SLAMF7 relapsed during the same period (Fig. 2). Similarly, as regards DSS, 100% of the patients without SLAMF7 expression succumbed to the disease during the 5-year follow-up period compared with only 25% of those with expressed SLAMF7 protein (Fig. 3). The survival results of the patients with BC in the present study are consistent with those in patients with MM, in whom a higher SLAMF7 mRNA expression was a significant prognosticator of a longer survival and has been proposed as a useful tool for classifying hematologic malignancies into molecular subgroups for therapeutic purposes (69). In addition, elotuzumab (a monoclonal antibody against SLAMF7 approved by the FDA in November, 2015), in combination with other targeted antimyeloma therapies that stimulate host immunity, has been shown to exert an effective immunotherapeutic effect (70), improving DFS and thus reducing relapse [as reviewed by Boudreault et al (71)]. Although immunotherapy is an established adjunct therapeutic strategy that improves the survival and treatment of cancer patients (72), SLAMF7 remains poorly studied in solid tumors. In addition to the present study, which documented the clear cytoplasmic protein expression in BC, SLAMF7 has also been shown to be expressed in colorectal cancer (37), and at the transcript level in both ovarian and cervical cancers (38,39); however, those studies did not evaluate its prognostic/predictive value. Consistent with the findings presented herein, data from TCGA have revealed that a low SLAMF7 gene expression is strongly associated with poor survival outcomes in ovarian cancer (61). Furthermore, the findings obtained herein were compared with those from other freely available transcriptomic data of SLAMF7 in cancer genomics databases, mainly the UCSC Xena or UALCAN databases. Using the UCSC Xena portal, the SLAMF7 transcript was expressed in the majority of the TCGA breast invasive carcinoma cohort (47), and this expression was significantly higher than that in normal breast tissues according to the UALCAN database (P<0.001) (73).

SLAMF7 is a transmembrane marker and a promising molecular marker that plays multiple immune-molecular and signaling roles in modulating the cellular immune response (Fig. 5). SLAMF7 is involved in the inhibition of T-cell proliferation, the overexpression of growth-promoting cytokines in B-cells and cytokine production following antigen stimulation (74). In NK cells, SLAMF7 mediates activating signals via Ewing's sarcoma-associated transcript 2 involving phospholipase Cγ1 and the ERK1/2 signaling pathways and calcium influx, leading to cell-mediated cytotoxicity (28,75). It also plays a critical role in mediating cellular adhesion in macrophages through SLAM family receptors (76).

Since SLAMF7 has an FDA-approved monoclonal antibody (elotuzumab), the results of the present study suggest that once validated, it may have immense potential for monoclonal antibody therapy, which could improve the prognosis and therapeutic outcomes of patients with BC. It can also serve as an additional molecular classifier and make a noticeable contribution as a prognosticator and therapeutic target, particularly for patients with TNBC where outcomes are still challenging. The present study revealed that only 10% of TNBC cases expressed SLAMF7, whereas, on the other hand, 78% of TPBC cases had no expression of SLAMF7. Further studies are warranted to further investigate the association between TNBC cases and SLAMF7 using larger BC cohorts. This research approach is essential in order to identify a promising therapeutic option for the aggressive TNBC molecular subtype, known by the limited treatment modalities compared with its TPBC counterpart.

It is important to highlight that the lack of SLAMF7 mRNA expression in the studied tumor tissues is a limitation of the present study, since it would be a valuable validation of the protein expression findings. Moreover, and as aforementioned, the molecular effects of SLAMF7 are affected not only by its level of expression, but also by its soluble fraction (sSLAMF7) shown to be involved in lymphocyte proliferation. The authors aim to perform additional studies in the future to investigate the mRNA expression patterns, roles and molecular mechanisms underlying the action of SLAMF7/sSLAMF7 in solid tumors in general and BC, in particular, in order to validate the IHC findings and optimize its use towards precision BC therapies.

In conclusion, to the best of our knowledge, the present study was the first to report the cytoplasmic expression of SLAMF7 in BC. The lack of or a low expression of SLAMF7 protein was associated with both tumor and vascular invasion. It was also a strong prognosticator of poor survival outcomes, including a higher number of BC recurrences and mortality. Therefore, elotuzumab may prove to be an additional targeted therapy for patients with BC.

 Acknowledgements

The author would like to thank Professor Abdelbaset Buhmeida, Center of Excellence in Genomic Medicine Research, King Abdulaziz University, for validating the immunohistochemistry scoring, as well as Ms. F. Yahia from the Department of Biochemistry, King Abdulaziz University, for improving and exporting Fig. 5 using Biorender.com.

 Availability of data and materials

The datasets used and/or analyzed during the current study are available from the corresponding author upon reasonable request.

 Author's contributions

MA is the sole contributor to this work. MA conceived and designed the study, analyzed the data and wrote the whole manuscript. MA confirms the authenticity of all the raw data. The author has read and approved the final manuscript.

 Ethics approval and consent to participate

Ethical approval for the present study was obtained from the Research Ethics Committee of The Center of Excellence in Genomic Medicine Research (IRB no. 08-CEGMR-02-ETH). The study was in line with the declaration of Helsinki. All participants provided signed informed consent before inclusion in this study.

 Patient consent for publication

Not applicable.

 Competing interests

The author declares that he has no competing interests.

 References FerlayJColombetMSoerjomataramIParkinDMPiñerosMZnaorABrayFCancer statistics for the year 2020: An overviewInt J Cancer149778789202110.1002/ijc.33588 SiegelRLMillerKDFuchsHEJemalACancer statistics, 2021CA Cancer J Clin71733202110.3322/caac.2165433433946 PfeifferRMWebb-VargasYWheelerWGailMHProportion of US trends in breast cancer incidence attributable to long-term changes in risk factor distributionsCancer Epidemiol Biomarkers Prev2712141222201810.1158/1055-9965.EPI-18-009830068516 GlobocanSaudi Arabia Fact SheetsInternational Agency for Research on Cancer (IARC)Lyon, Francehttps://gco.iarc.fr/today/data/factsheets/populations/682-saudi-arabia-fact-sheets.pdfApril72022 AlbeshanSMAlashbanYIIncidence trends of breast cancer in Saudi Arabia: A Joinpoint regression analysis (2004–2016)J King Saud Univ Sci33101578202110.1016/j.jksus.2021.101578 JaziehARDa'arOBAlkaiyatMZaatrehYASaadAABustamiRAlrujaibMAlkattanKCancer incidence trends from 1999 to 2015 and contributions of various cancer types to the overall burden: Projections to 2030 and extrapolation of economic burden in Saudi ArabiaCancer Manag Res1196659674201910.2147/CMAR.S22266732009819 AlbeshanSMMackeyMGHossainSZAlfuraihAABrennanPCBreast cancer epidemiology in gulf cooperation council countries: A regional and international comparisonClin Breast Cancer18e381e392201810.1016/j.clbc.2017.07.00628781021 AssidiMJafriMAAbu-ElmagdMN PushparajPSaddickSMessaoudiSAlkhatabiHAl-MaghrabiJAnfinanNSaitMPrognostic value of E-Cadherin and its tumor suppressor role in Saudi women with advanced epithelial ovarian cancerLibyan J Med161994741202110.1080/19932820.2021.199474134720069 LumachiFLuisettoGMM BassoSBassoUBrunelloACamozziVEndocrine therapy of breast cancerCurrent Med Chem18513522201110.2174/09298671179448017721143113 HuangCYJuDTChangCFReddyPMVelmuruganBKA review on the effects of current chemotherapy drugs and natural agents in treating non-small cell lung cancerBiomedicine (Taipei)723201710.1051/bmdcn/201707042329130448 AllisonKHHammondMEHDowsettMMcKerninSECareyLAFitzgibbonsPLHayesDFLakhaniSRChavez-MacGregorMPerlmutterJEstrogen and progesterone receptor testing in breast cancer: ASCO/CAP guideline updateJ Clin Oncol3813461366202010.1200/JCO.19.0230931928404 PurdieCAQuinlanPJordanLBAshfieldAOgstonSDewarJAThompsonAMProgesterone receptor expression is an independent prognostic variable in early breast cancer: A population-based studyBr J Cancer110565572201410.1038/bjc.2013.75624300977 PetroniSCaldarolaLScamarcioRGiottaFLatorreAMangiaASimoneGFISH testing of HER2 immunohistochemistry 1+ invasive breast cancer with unfavorable characteristicsOncol Lett1231153122201610.3892/ol.2016.512527899970 BrownJRDiGiovannaMPKilleleaBLanninDRRimmDLQuantitative assessment Ki-67 score for prediction of response to neoadjuvant chemotherapy in breast cancerLab Invest9498106201410.1038/labinvest.2013.12824189270 LampeljMArkoDCas-SikosekNKavalarRRavnikMJezersek-NovakovicBDobnikSDovnikNFTakacIUrokinase plasminogen activator (uPA) and plasminogen activator inhibitor type-1 (PAI-1) in breast cancer-correlation with traditional prognostic factorsRadiol Oncol49357364201510.2478/raon-2014-004926834522 ParralesAIwakumaTTargeting oncogenic mutant p53 for cancer therapyFront Oncol5288201510.3389/fonc.2015.0028826732534 BiHLiSQuXWangMBaiXXuZAoXJiaZJiangXYangYWuHDEC1 regulates breast cancer cell proliferation by stabilizing cyclin E protein and delays the progression of cell cycle S phaseCell Death Dis6e1891e1891201510.1038/cddis.2015.24726402517 Al-KeilaniMSElstatyRIAlqudahMAAlkhateebAMImmunohistochemical expression of substance P in breast cancer and its association with prognostic parameters and Ki-67 indexPLoS One16e0252616202110.1371/journal.pone.025261634086748 TrayNWeberJSAdamsSPredictive biomarkers for checkpoint immunotherapy: Current status and challenges for clinical applicationCancer Immunol Res611221128201810.1158/2326-6066.CIR-18-021430279188 EmensLACruzCEderJPBraitehFChungCTolaneySMKuterINandaRCassierPADelordJPLong-term clinical outcomes and biomarker analyses of Atezolizumab therapy for patients with metastatic Triple-negative breast cancer: A phase 1 studyJAMA Oncol57482201910.1001/jamaoncol.2018.422430242306 WaldmanADFritzJMLenardoMJA guide to cancer immunotherapy: From T cell basic science to clinical practiceNat Rev Immunol20651668202010.1038/s41577-020-0306-532433532 KeefeDMKBatemanEHPotential successes and challenges of targeted cancer therapiesJ Natl Cancer Inst Monogr2019lgz008201910.1093/jncimonographs/lgz00831425592 AkbulutHBabahanCAbgarmiSAOcalMBeslerMRecent advances in cancer stem cell targeted therapyCrit Rev Oncog24120201910.1615/CritRevOncog.201802957431679215 TaiYTDillonMSongWLeibaMLiXFBurgerPLeeAIPodarKHideshimaTRiceAGAnti-CS1 humanized monoclonal antibody HuLuc63 inhibits myeloma cell adhesion and induces antibody-dependent cellular cytotoxicity in the bone marrow milieuBlood11213291337200810.1182/blood-2007-08-10729217906076 BolesKSMathewPAMolecular cloning of CS1, a novel human natural killer cell receptor belonging to the CD2 subset of the immunoglobulin superfamilyImmunogenetics52302307200110.1007/s00251000027411220635 HsiEDSteinleRBalasaBSzmaniaSDraksharapuAShumBPHuseniMPowersDNanisettiAZhangYCS1, a potential new therapeutic antibody target for the treatment of multiple myelomaClin Cancer Res1427752784200810.1158/1078-0432.CCR-07-424618451245 LonialSDimopoulosMPalumboAWhiteDGrosickiSSpickaIWalter-CroneckAMoreauPMateosMVMagenHElotuzumab therapy for relapsed or refractory multiple myelomaN Engl J Med373621631201510.1056/NEJMoa150565426035255 BouchonACellaMGriersonHLCohenJIColonnaMCutting edge: Activation of NK cell-mediated cytotoxicity by a SAP-independent receptor of the CD2 familyJ Immunol16755175521200110.4049/jimmunol.167.10.551711698418 KumaresanPRLaiWCChuangSSBennettMMathewPACS1, a novel member of the CD2 family, is homophilic and regulates NK cell functionMol Immunol3918200210.1016/S0161-5890(02)00094-912213321 ChenJZhongMCGuoHDavidsonDMishelSLuYRheeIPérez-QuinteroLAZhangSCruz-MunozMESLAMF7 is critical for phagocytosis of haematopoietic tumour cells via Mac-1 integrinNature544493497201710.1038/nature2207628424516 PazinaTJamesAMMacFarlane AWIVBezmanNAHenningKABeeCGrazianoRFRobbinsMDCohenADCampbellKSThe anti-SLAMF7 antibody elotuzumab mediates NK cell activation through both CD16-dependent and-independent mechanismsOncoimmunology6e1339853201710.1080/2162402X.2017.133985328932638 SimmonsDPNguyenHNGomez-RivasEJeongYJonssonAHChenAFLangeJKDyerGSBlazarPEarpBESLAMF7 engagement superactivates macrophages in acute and chronic inflammationSci Immunol7eabf2846202210.1126/sciimmunol.abf284635148199 CampbellKSCohenADPazinaTMechanisms of NK cell activation and clinical activity of the therapeutic SLAMF7 antibody, elotuzumab in multiple myelomaFront Immunol92551201810.3389/fimmu.2018.0255130455698 LonialSDimopoulosMPalumboAWhiteDGrosickiSSpickaIWalter-CroneckAMoreauPMateosMVMagenHElotuzumab therapy for relapsed or refractory multiple myelomaN Engl J Med373621631201510.1056/NEJMoa150565426035255 LeeJLRohSAKimCWKwonYHHaYJKimSKKimSYChoDHKimYSKimJCClinical assessment and identification of immuno-oncology markers concerning the 19-gene based risk classifier in stage IV colorectal cancerWorld J Gastroenterol2513411354201910.3748/wjg.v25.i11.134130918427 LiXZhouHHuangWWangXMengMHouZLiaoLTangWXieYWangRRetrospective analysis of the efficacy of adjuvant cytokine-induced killer cell immunotherapy combined with chemotherapy in colorectal cancer patients after surgeryClin Transl Immunol11e1368202210.1002/cti2.136835079378 RohSAKwonYHLeeJLKimSKKimJCSLAMF7 and TREM1 mediate immunogenic cell death in colorectal cancer cells: Focus on microsatellite stabilityAnticancer Res4154315444202110.21873/anticanres.1535534732412 SuRJinCZhouLGaoYKuangMLiLXiangJConstruction of a ceRNA network of hub genes affecting immune infiltration in ovarian cancer identified by WGCNABMC Cancer21970202110.1186/s12885-021-08711-w34461858 ChenHWangTHuangSZengPNew novel non-MHC genes were identified for cervical cancer with an integrative analysis approach of transcriptome-wide association studyJ Cancer12840848202110.7150/jca.4791833403041 SunHKimERyuJLeeHShinEALeeMLeeHLeeHJYoonJHSongDGTM4SF5-mediated liver malignancy involves NK cell exhaustion-like phenotypesCell Mol Life Sci7949202110.1007/s00018-021-04051-x34921636 O'ConnellPBlakeMKPepelyayevaYHyslopSGodbehereSAngaritaAMPereira-HicksCAmalfitanoAAldhamenYAAdenoviral delivery of an immunomodulatory protein to the tumor microenvironment controls tumor growthMol Ther Oncolytics24180193202110.1016/j.omto.2021.12.00435036523 Al-MaghrabiJEmamEGomaaWSaggafMBuhmeidaAAl-QahtaniMAl-AhwalMc-MET immunostaining in colorectal carcinoma is associated with local disease recurrenceBMC Cancer15676201510.1186/s12885-015-1662-626459369 NedjadiTAl-MaghrabiJAssidiMDallolAAl-KattabiHChaudharyAAl-SayyadAAl-AmmariAAbuzenadahABuhmeidaAAl-QahtaniMPrognostic value of HER2 status in bladder transitional cell carcinoma revealed by both IHC and BDISH techniquesBMC Cancer16653201610.1186/s12885-016-2703-527539085 AssidiMYahyaFMAl-ZahraniMHElkhatibRZariAElaimiAAl-MaghrabiJDallolABuhmeidaAAbu-ElmagdMLeptin protein expression and promoter methylation in ovarian cancer: A strong prognostic value with theranostic promisesInt J Mol Sci2212872202110.3390/ijms22231287234884678 BuhmeidaADallolAMerdadAAl-MaghrabiJGariMAAbu-ElmagdMMChaudharyAGAbuzenadahAMNedjadiTErmiahEHigh fibroblast growth factor 19 (FGF19) expression predicts worse prognosis in invasive ductal carcinoma of breastTumour Biol3528172824201410.1007/s13277-013-1374-y24248542 ChandrashekarDSBashelBBalasubramanyaSAHCreightonCJPonce-RodriguezIChakravarthiBVSKVaramballySUALCAN: A portal for facilitating tumor subgroup gene expression and survival analysesNeoplasia19649658201710.1016/j.neo.2017.05.00228732212 GoldmanMJCraftBHastieMRepečkaKMcDadeFKamathABanerjeeALuoYRogersDBrooksANVisualizing and interpreting cancer genomics data via the Xena platformNat Biotechnol38675678202010.1038/s41587-020-0546-832444850 CroninKALakeAJScottSShermanRLNooneAMHowladerNHenleySJAndersonRNFirthAUMaJAnnual report to the nation on the status of cancer, part I: National cancer statisticsCancer12427852800201810.1002/cncr.3155129786848 JiangMYangJSLiKLiuJJingXGTangMQInsights into the theranostic value of precision medicine on advanced radiotherapy to breast cancerInt J Med Sci18626638202110.7150/ijms.4954433437197 SocietyACCancer facts & figures 2012AtlantaAmerican Cancer Society9112012 LaiFMChenPKuHCLeeMSChangSCChangTMLiouSHA case-control study of parity, age at first full-term pregnancy, breast feeding and breast cancer in Taiwanese womenProc Natl Sci Counc Repub China B20717719968956522 PerouCMSørlieTEisenMBvan de RijnMJeffreySSReesCAPollackJRRossDTJohnsenHAkslenLAMolecular portraits of human breast tumoursNature406747752200010.1038/3502109310963602 Reis-FilhoJSPusztaiLGene expression profiling in breast cancer: Classification, prognostication, and predictionLancet37818121823201110.1016/S0140-6736(11)61539-022098854 Garrido-CastroACLinNUPolyakKInsights into molecular classifications of triple-negative breast cancer: Improving patient selection for treatmentCancer Discov9176198201910.1158/2159-8290.CD-18-117730679171 DaiXXiangLLiTBaiZCancer hallmarks, biomarkers and breast cancer molecular subtypesJ Cancer712811294201610.7150/jca.1314127390604 GoldhirschAWoodWCCoatesASGelberRDThürlimannBSennHJStrategies for subtypes-dealing with the diversity of breast cancer: Highlights of the St. Gallen International Expert Consensus on the Primary Therapy of Early Breast Cancer 2011Ann Oncol2217361747201110.1093/annonc/mdr30421709140 KimJRHortonNCMathewSOMathewPACS1 (SLAMF7) inhibits production of proinflammatory cytokines by activated monocytesInflamm Res62765772201310.1007/s00011-013-0632-123695528 LiXZhouHHuangWWangXMengMHouZLiaoLTangWXieYWangRRetrospective analysis of the efficacy of adjuvant cytokine-induced killer cell immunotherapy combined with chemotherapy in colorectal cancer patients after surgeryClin Transl Immunol11e1368202210.1002/cti2.136835079378 ThulPJLindskogCThe human protein atlas: A spatial map of the human proteomeProtein Sci27233244201810.1002/pro.330728940711 UhlénMFagerbergLHallströmBMLindskogCOksvoldPMardinogluASivertssonÅKampfCSjöstedtEAsplundATissue-based map of the human proteomeScience3471260419201510.1126/science.126041925613900 UhlenMZhangCLeeSSjöstedtEFagerbergLBidkhoriGBenfeitasRArifMLiuZEdforsFA pathology atlas of the human cancer transcriptomeScience357eaan2507201710.1126/science.aan250728818916 ZekriJSaadeddinAAlharbiHFrequency and clinical characteristics of HER2 over-expressed breast cancer in Saudi Arabia: A retrospective studyBMC Womens Health2110202110.1186/s12905-020-01159-333407382 WeigelMTDowsettMCurrent and emerging biomarkers in breast cancer: Prognosis and predictionEndocrine-related Cancer17R245R262201010.1677/ERC-10-013620647302 SagguSRehmanHAbbasZKAnsariAARecent incidence and descriptive epidemiological survey of breast cancer in Saudi ArabiaSaudi Med J3611761180201510.15537/smj.2015.10.1226826446327 AlbasriAHussainyASSundkjiIAlhujailyAHistopathological features of breast cancer in Al-Madinah region of Saudi ArabiaSaudi Med J3514891493201425491214 HowladerNNooneAKrapchoMMillerDBrestAYuMRuhlJTatalovichZMariottoALewisDRSEER cancer statistics review, 1975–2016, National Cancer InstituteBethesda, MDhttps://seer.cancer.gov/csr/1975_2016/based on November 2018 SEER data submission, posted to the SEER web siteApril2019 NajjarHEassonAAge at diagnosis of breast cancer in Arab nationsInt J Surg8448452201010.1016/j.ijsu.2010.05.01220601253 MüllerLPawelecGAging and immunity-impact of behavioral interventionBrain Behav Immunity39822201410.1016/j.bbi.2013.11.01524315935 ValcárcelLVAmundarainAKulisMCharalampopoulouSMelnickASan MiguelJMartín-SuberoJIPlanesFJAgirreXProsperFGene expression derived from alternative promoters improves prognostic stratification in multiple myelomaLeukemia3530123016202110.1038/s41375-021-01263-933972667 MalaerJDMathewPACS1 (SLAMF7, CD319) is an effective immunotherapeutic target for multiple myelomaAm J Cancer Res716371641201728861320 BoudreaultJSTouzeauCMoreauPThe role of SLAMF7 in multiple myeloma: Impact on therapyExpert Rev Clin Immunol136775201710.1080/1744666X.2016.120911227376202 PhamTRothSKongJGuerraGNarasimhanVPereiraLDesaiJHeriotARamsayRAn update on immunotherapy for solid tumors: A reviewAnn Surg Oncol2534043412201810.1245/s10434-018-6658-430039324 ChandrashekarDSKarthikeyanSKKorlaPKPatelHShovonARAtharMNettoGJQinZSKumarSManneUUALCAN: An update to the integrated cancer data analysis platformNeoplasia251827202210.1016/j.neo.2022.01.00135078134 DetreCKeszeiMRomeroXTsokosGCTerhorstCSLAM family receptors and the SLAM-associated protein (SAP) modulate T cell functionsSemin Immunopathol32157171201010.1007/s00281-009-0193-020146065 WuNVeilletteASLAM family receptors in normal immunity and immune pathologiesCurr Opin Immunol384551201610.1016/j.coi.2015.11.00326682762 ClausMUrlaubDFasbenderFWatzlCSLAM family receptors in natural killer cells-mediators of adhesion, activation and inhibition via cis and Trans interactionsClin Immunol2043742201910.1016/j.clim.2018.10.01130359773

Cytoplasmic expression patterns of signaling lymphocytic activation molecule F7 in primary BC tissues, as shown using immunohistochemical staining. (A) Negative (0) cytoplasmic expression, (B) weak (1+) cytoplasmic expression, (C) moderate (2+) cytoplasmic expression, (D) strong (3+) cytoplasmic expression, (E) distribution of low (0, 1+) vs. high (2+, 3+) protein expression of SLAMF7 among primary BC tissues of the studied cohort. BC, breast cancer.

Cytoplasmic SLAMF7 expression patterns in the primary lymph node-positive breast cancer cohort using the cut-off [negative (0) vs. positive (1+, 2+ and 3+)] as a determinant of disease-free survival in univariate (Kaplan-Meier) analysis (P<0.001, log-rank test). SLAMF7, signaling lymphocytic activation molecule F7.

Cytoplasmic SLAMF7 expression patterns in the primary lymph node-positive breast cancer cohort using the cut-off [negative (0) vs. positive (1+, 2+ and 3+)] as a determinant of disease-specific survival in univariate (Kaplan-Meier) analysis (P<0.008, log-rank test). SLAMF7, signaling lymphocytic activation molecule F7.

Student's t-test comparison between the number of signaling lymphocytic activation molecule F7 transcripts in breast invasive cancer compared to normal breast tissue according to the UALCAN database. *P<0.001 vs. normal. TCGA, The Cancer Genome Atlas.

An overview of the main molecular, cellular and signaling functions of SLAMF7 as regards its involvement in the immune system, as well as in other tissues. SLAMF7, signaling lymphocytic activation molecule F7.

Association between SLAMF7 protein expression patterns and the clinicopathological features of patients with breast cancer.

SLAMF7 protein expression
Features No. of cases (Low) (%) (High) (%) P-value
Age, years 0.007a
  <50 143 (51.4%) 105 (73) 38 (27)
  >50 134 (48.2%) 116 (87) 18 (13)
  Missed data 1 (0.4%)
Tumor invasion 0.008a
  Negative 3 (1.1%) 0 (0) 3 (100)
  Positive 258 (92.8%) 209 (81) 49 (19)
  Missed data 17 (6.1%)
ER and PR hormonal status 0.912
  ER−, PR− 72 (25.9%) 59 (82) 13 (18)
  ER+, PR+ 126 (45.3%) 104 (83) 22 (17)
  Missed data 80 (28.8)
HER2 protein status 0.255
  Negative 150 (54%) 118 (84) 23 (16)
  Positive 79 (28.4%) 70 (78) 20 (22)
  Borderline 13 (4.7)
  Missed data 36 (12.9%)
ER, PR and HER2 status 0.579
  Triple-negative 30 (10.8%) 26 (87) 4 (13)
  Triple-positive 42 (15.1%) 33 (79) 9 (21)
  Missed data 206 (74.1%)
Vascular invasion 0.050
Negative 84 (30.2%) 64 (76) 20 (24)
  Positive 126 (45.3%) 109 (86) 17 (14)
  Missed data 68 (24.5%)
Tumor margin 0.713
  Negative 222 (79.9%) 182 (82) 40 (18)
  Positive 29 (10.4%) 23 (79) 6 (21)
  Missed data 27 (9.7%)
Tumor size, cm 0.298
  0-3 76 (27.3%) 56 (74) 20 (26)
  3-6 136 (48.9%) 112 (82) 24 (18)
  >7 40 (14.4%) 33 (83) 7 (17)
  Missed data 26 (9.4%)
Tumor grade 0.844
  Grade 1 34 (12.2%) 27 (79) 7 (21)
  Grade 2 135 (48.6%) 110 (82) 25 (18)
  Grade 3 81 (29.1%) 64 (79) 17 (21)
  Missed data 28 (10.1%)
Histopathological type 0.466
  Invasive ductal 258 (92.8%) 207 (80) 51 (20)
  Other 18 (6.5%) 13 (72) 5 (28)
  Missed data 2 (0.7%)
Disease recurrence 0.542
  Yes 40 (14.4%) 34 (85) 6 (15)
  No 112 (40.3%) 90 (80) 22 (20)
  Missed data 126 (45.3%)
Status at end point 0.338
  Succumbed to the disease 25 (9%) 18 (72) 7 (28)
  Alive 66 (23.7%) 53 (80) 13 (20)
  Missed data 187 (67.3%)

Data were analyzed using Fisher's exact text.

P<0.05. SLAMF7, signaling lymphocytic activation molecule F7.

Cox regression analysis of the prognostic values of cytoplasmic SLAMF7 protein expression, age at diagnosis, lymph node status, grade and tumor vascular invasion in association with the survival of patients with breast cancer.

Parameter P-value SE value Relative risk 95% CI
SLAMF7 0.58 0.431 1.270 0.338-1.830
Age at diagnosis 0.12 0.425 0.512 0.848-4.490
Lymph node status 0.10 0.453 0.478 0.861-5.077
Tumor grade 0.42 0.307 1.282 0.428-1.423
Tumor vascular invasion 0.060 0.489 2.50 0.154-1.043

SLAMF7, signaling lymphocytic activation molecule F7.