The expression of RCAS1 and tumor infiltrating lymphocytes in patients with T3 gastric carcinoma
Background: This study aimed to assess the prognostic value of receptor binding cancer antigen expressed on SiSo cells (RCAS1) expression and host immune response in gastric carcinomas.
Methods: We investigated the relationship between RCAS1 expression, density of tumor-infiltrating lymphocytes (TIL), and clinicopathological findings in 129 patients with T3 gastric carcinoma who underwent curative surgery.
Results: RCAS1 immunoreactivity was detected in the membrane and cytoplasm of tumor cells. Positive immunoreactivity for RCAS1 was detected in 70 patients (54.3%) and high expression levels of RCAS1 were found in 33 patients (25.6%). The expression of RCAS1 significantly correlated with the histological type of carcinoma and lymph node metastasis. Apoptotic rates in TILs showed marginally higher significance in patients with high RCAS1 expression than in those with low expression. The 5-year survival rates were 77.9% in patients with low RCAS1 expression and 48.4% in those with high RCAS1 expression. Although there was no significant difference in survival between the patients with marked and slight infiltration of TILs, frequent apoptosis in TILs indicated significantly worse prognosis. Patients with low RCAS1 expression survived significantly longer than those with high RCAS1 expression, as did those patients with a high rate of apoptosis in TILs. Multivariate analysis revealed that RCAS1 expression, as well as tumor size and lymph node metastasis, was an independent prognostic factor.
Conclusions: The expression of RCAS1 was significantly correlated with poor prognosis in patients with T3 gastric carcinoma. RCAS1 protein may play an important role in the evasion of tumor cells from immunological defense mechanisms in human gastric carcinoma.