The clinical and pathological significance of RCAS1 expression as a prognostic biomarker in non-small cell lung cancer.

BACKGROUND Lung cancer remains a major health problem due to its incidence and mortality. Receptor-binding cancer antigen expressed on SiSo cells (RCAS1) is a protein that can be expressed in cancer cells and is involved in tumor cell escape from immune system surveillance. AIM The aim of this study was to evaluate the clinical significance of immunohistochemical staining for RCAS1 in non-small cell lung cancer (NSCLC). MATERIALS AND METHODS Tissue microarrays of tumor specimens from 112 consecutive patients with newly diagnosed primary NSCLC were constructed. RCAS1 and Ki-67 immunohistochemistry were studied through computerized image analysis. Associations between RCAS1 and Ki-67 expression and clinico-pathological variables and survival were analyzed. RESULTS RCAS1 expression was higher in grade III tumors (p=0.009), 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). Moreover, there was an inverse correlation of overall survival with RCAS1 (hazard ratio=0.99, p<0.001) and Ki-67 (hazard ratio=1.05, p=0.003) levels. Particularly, patients with higher expression of RCAS1 or Ki-67 had a significantly shorter survival than those with lower expression. CONCLUSION RCAS1 could be a useful immunohistochemical biomarker, indicating not only tumor aggressiveness but also a poorer prognosis for patients with NSCLC.