High Expression Of Tumor-Associated Antigen Rcas1 In Pancreatic Ductal Adenocarcinoma Is An Unfavorable Prognostic Marker

RCASI (receptor-binding cancer antigen expressed on SiSo cells) is a recently identified human tumor-associated antigen expressed on various cancer cells. It is thought that tumor cells evade immune surveillance by expression of RCASI, which induces apoptotic cell death in receptor-positive immune cells. The purpose of our study was to investigate the relation between RCASI expression and the clinicopathological variables and clinical outcome in patients with pancreatic adenocarcinoma. Immunohistochemical analysis for RCASI was performed on paraffin-embedded specimens of 80 patients (mean age, 62 years) who underwent surgical resection for pancreatic adenocarcinoma. Of the 80 specimens, 77 (96%) were positive for RCASI. No significant correlation was found between RCAS I expression and age, gender, depth of invasion, tumor diameter, surgical margin, lymphatic invasion, venous invasion or histopathological grading. Borderline correlations between RCAS I expression were noted for lymph node metastasis and stage (p = 0.0608 and 0.0934, respectively). RCASI expression was very frequently observed and the survival of patients with high RCASI expression was significantly shorter than that of those with low expression (p = 0.0012). Multivariate analysis using the Cox regression model indicated that high RCASI expression was an independent prognostic factor (risk ratio, 3.090; p = 0.0090). These results suggested that RCASI might be a significant tumor marker for pancreatic adenocarcinoma and an unfavorable predictor for prognosis of patients who have undergone surgical resection. (C) 2002 Wiley-Liss, Inc.