Lung cancer is the first cause of cancer related deaths. RCAS1 (Receptor-binding Cancer Antigen expressed on SiSo cells) is a protein that is expressed in different types of cancer and seems to be involved in the process of the tumour cells’ escape from the immune system surveillance (immunoescape). CD3 (cluster of differentiation CD3), is an antigen that is part of the T cell receptor (TCR) complex on a mature T lymphocyte. Tumor infiltrating lymphocytes (TILs) have been correlated with patients’ survival in several neoplasms.
The aim of this study was to evaluate the clinical importance of RCAS1 and CD3 expression in non-small cell lung cancer (NSCLC). Tissue microarrays of tumor specimens from 112 patients with newly diagnosed NSCLC were constructed. The sections were stained with monoclonal antibodies against RCAS1, Ki-67 and CD3 using immunohistochemistry and they were studied through classical pathological evaluation and computerized image analysis. Correlations among RCAS1, Ki-67 and CD3 expression, clinicopathological variables and survival were analyzed. In all cases p-value ≤ 0.05 was considered significant.
112 patients were included in this study with mean age 63.6 years old and 83% were males. RCAS1 expression was higher in grade III tumors comparing with grade I (p = 0.004) and grade II (p = 0.005) regardless of the histological type and in adenocarcinomas with lymphovascular invasion (p = 0.014). A positive correlation between RCAS1 and Ki-67 levels was observed (p = 0.002). There was an inverse correlation of overall survival with RCAS1 and Ki-67 levels and patients with higher expression of RCAS1 or Ki-67 had a significantly shorter survival. Also, an inverse correlation between RCAS1 expression and the percentage of CD3(+) TILs was found. Finally, a positive correlation between the percentage of CD3(+) TILs and the patients’ overall survival (p = 0.094) was observed.
CD3 expression was negative correlated with RCAS1 and positive with overall survival in patients with NSCLC. RCAS1 could be a useful biomarker indicating tumor aggressiveness and immunoescape of cancer cells. Further studies needed to elucidate the possible role of RCAS1 as a biomarker in immunooncology era.
Clinical trial identification
Legal entity responsible for the study
Medical School, National and Kapodistrian University of Athens.
Has not received any funding.
Hellenic Society of Medical Oncology (HeSMO).
All authors have declared no conflicts of interest.