Significance of RCAS1 antigen in hepatocellular, cholangiocenular and pancreatic carcinomas

Since receptor-binding cancer antigen expressed on SiSo cells (RCAS1) was first reported as a tumor-associated antigen of gynecologic cancer, its function and practical value as a tumor marker have been investigated in various types of carcinomas. Basic research has indicated that RCAS1 expression in cancer cells contributes to the evasion from immune surveillance and progression of carcinomas. The clinical significance of RCAS1 expression in hepatobiliary and pancreatic carcinomas has also been investigated. In this review, we summarize the clinical application of RCAS1 antigen in hepatic and pancreaticobiliary diseases. We present new data and review current knowledge about the potential of RCAS1 as a tumor marker and the relationship between RCAS1 expression and clinicopathologic parameters. We found that the clinical function of RCAS1 appeared to differ according to the type of carcinoma. In hepatocellular carcinoma, the clinical significance of histological RCAS1 expression was controversial and that of serum RCAS1 levels showed little clinical value. In pancreaticobiliary cancers, high RCAS1 expression in tissue samples was an unfavorable independent prognostic factor. Serum RCAS1 was a superior tumor marker reflecting the disease activity in biliary carcinoma. In pancreatic cancer, serum RCAS1 levels were less useful than in biliary carcinoma but may be available for genetically CA19-9-negative patients and for CA19-9-non-producing cancer. This review also offers suggestions for future studies. (C) 2005 Blackwell Publishing Asia Pty Ltd.