Lung cancer is the most common malignant tumor. The morbidity and mortality rates rank first among all malignant tumors, seriously threatening human health (1). Lung cancer includes small cell lung cancer (SCLC) and non-small cell lung cancer (NSCLC), the latter of which is dominant (2). The early clinical symptoms of NSCLC are atypical, so the patients are in the middle and advanced stage once diagnosed, with unsatisfactory efficacy and poor prognosis. In recent years, the efficacy of specific gene- or protein-targeted therapies for middle and advanced NSCLC has greatly improved. However, the prognosis of NSCLC is still very poor and the 5-year survival rate has not improved. Therefore, study on the prognostic factors of NSCLC would be helpful for effective judgment of the prognosis and the formulation of individualized treatment plan (3). Metastasis is the main cause of death of patients (4,5). Metastasis-associated protein 1 (MTA1) plays an important role in tumor metastasis and often serves as a potential indicator for malignant potential in clinic (6). Some studies have reported that MTA1 protein expression is associated with invasiveness, metastasis and clinical outcome in patients with NSCLC (7–9). Computed tomography (CT) examination is a conventional examination method for NSCLC, which can fully reflect the pathophysiological and molecular biological characteristics of tumors, and it has important value in guiding the diagnosis and therapeutic evaluation (10,11). However, the relationship between MTA1 protein expression and CT features has not been investigated so far. It was hypothesized that there was some correlation between the expression of MTA1 protein and CT features. Therefore, actively exploring the associations between the imaging features of NSCLC and molecular markers can provide a reliable theoretical basis for targeted therapy of NSCLC.

NSCLC is a malignant tumor originating from the bronchial mucous epithelium, its pathogenesis is not fully clear. It is generally believed that smoking, occupational carcinogens, air pollution, ionizing radiation, diet and nutrition, hereditary and genetic changes are the major precipitating factors, under the influence of which the carcinogens will cause damage to lung tissues. Due to the low immunity of the elderly, it is difficult for the self-defense and scavenging system of the body's immune mechanism to completely eliminate these carcinogens, so that the inflammatory response is induced, and abnormal changes are caused in the microenvironment of lungs, ultimately leading to the formation of malignant tumors (13–15). Due to atypical early symptoms, NSCLC is usually diagnosed in the middle and advanced stage, during which the tumor is prone to metastasis and patients have poor prognosis (16).

MTA1 is a recently discovered protein associated with tumor metastasis, and it belongs to the tumor metastasis-associated protein family (17). Related studies have confirmed that the expression level of MTA1 is extremely low in normal tissues but obviously high in malignant tumor tissues, and it has a close association with tumor metastasis (18). In this study, the positive expression rate of MTA1 in 98 patients was 60.20% (59/98), and MTA1 was mainly expressed in the nucleus of carcinoma tissues. The positive expression of MTA1 was higher in poorly differentiated carcinoma than that in moderately differentiated and well differentiated carcinoma, and the MTA1 expression was very low in para-carcinoma normal tissues. This is because MTA1 can be detected in the nucleus of cancer tissues due to its high hydrophilicity and no transmembrane feature. In this study, the expression of MTA1 was associated with the degree of differentiation, stage and lymph node metastasis (P<0.05), but not with age, gender or tissue type (P>0.05). The reason is that MTA1 can inhibit ER gene transcription, thereby promoting down-regulation of ER expression, and facilitating the proliferation, invasion and metastasis of tumor cells, which make the prognosis of patients poorer and shorten their survival time.

CT examination has important value in the clinical diagnosis and treatment of NSCLC, characterized by clear images and short scanning time, and it is not influenced by surrounding tissues and organs (19). CT examination can be used to accurately observe the mass of NSCLC and to assess whether there is enlargement of lymph nodes and metastasis (20). With the development of imaging genomics, the NSCLC tissues can be quantitatively analyzed, so that the images can be converted into researchable data to reveal the intrinsic relation between tumor imaging features and molecular markers, which is of positive significance in predicting related gene mutations, and can offer strong support to targeted therapy of NSCLC (21). In this study, there was overexpression of MTA1 in tumor tissues in elderly NSCLC patients with spicule sign, pleural indentation sign and lymph node metastasis sign in CT images, indicating that patients with high expression of MTA1 are more prone to spicule sign, pleural indentation sign and lymph node metastasis sign. CT perfusion imaging technique can continuously scan the lesion area after high-pressure intravenous injection of contrast agent, thereby reflecting the hemodynamics of tumor tissues (22,23). In this study, there were no obvious differences in BV, BF and TTP between high expression MTA1 group and low expression MTA1 group. PMB was higher in high expression MTA1 group than that in low expression MTA1 group (P<0.05). The possible reason is that the overexpression of MTA1 will regulate the cell transcription level and affects tumor angiogenesis, but such a pro-angiogenic effect is not significant enough to alter the CT perfusion parameters BV, BF and TTP. However, in the case of MTA1 overexpression, the tumor is more prone to hematogenous metastasis, and PMB is obviously increased. As far as we know, MAT1 can only be detected in tissue, but not in the blood. In clinic, the lung tissues of patients were not always acquired for some reasons while CT examination was easy to obtain. The results of this study provide more evidence for targeted therapy of elderly NSCLC.

In conclusion, the expression of MTA1 has close associations with the CT features, pathology and prognosis of elderly NSCLC patients, which has positive guiding significance for targeted therapy of elderly with NSCLC.