Serum receptor-binding cancer antigen expressed on SiSo cells (RCAS1) as a diagnostic and prognostic marker for non-small cell lung cancer.

BACKGROUND: Receptor-binding cancer antigen expressed on SiSo cells (RCAS1) is a human tumor-associated antigen that induces cell-cycle arrest and apoptosis in cells bearing the RCAS1 receptor. The aim of the study was to elucidate the diagnostic and prognostic value of RCAS1 levels in patients with non-small cell lung cancer. METHODS: Sera collected from 30 healthy volunteers, 40 patients with benign lung diseases and 97 non-small cell lung cancer cases were subjected to RCAS1 ELISA, and relationships between serum RCAS1 and clinical characteristics were evaluated. RESULTS: Serum RCAS1 levels were higher in the non-small cell lung cancer group than in the healthy volunteers and benign lung disease groups (P <0.001). With a cutoff level 19.8 U/ml, RCAS1 had a sensitivity of 87.6%, a specificity of 82.5% and an accuracy of 86.1% for non-small cell lung cancer. Univariate analysis revealed that non-small cell lung cancer patients with elevated RCAS1 levels had significantly shorter overall survival (P = 0.042) than the other two groups. By multivariate analysis, serum RCAS1 was identified as an independent prognostic factor (P = 0.003). CONCLUSIONS: Assessment of serum RCAS1 levels could be considered as a diagnostic and prognostic marker in non-small cell lung cancer.