Clinical significance of retinoblastoma protein (pRB) expression in esophageal squamous cell carcinoma

Background and Objectives: The goal was to evaluate the clinicopathological significance of retinoblastoma gene product (pRB) expression in esophageal squamous cell carcinoma. Methods: We investigated abnormal pRB expression in tumors in 191 patients using an immunohistochemical method in conjunction with anti-RB protein ant ibody. Surgically resected esophageal squamous cell carcinomas were examine d by immunohistochemical analysis for altered pRB expression. Results: Decreased pRB nuclear staining indicating loss of RE function occu rred in 82 (43%) of the cases studied. The incidence of decreased pRB expre ssion was higher in tumors with invasion to the adventitia (50%) than in tu mors without invasion to the adventitia (33%, P = 0.0188). In addition, the incidence of decreased pRB expression was higher in tumors with lymph node metastasis (50%) than in those without (34%, P = 0.0346) The 3-year surviv al rates of 82 patients who had tumors with decreased pRB expression (30%) was significantly lower than that of 109 patients who had tumors with norma l pRB expression (52%, P = 0.0032). However, in the multivariate survival a nalysis, pRB expression wets not an independent prognostic factor for patie nts with esophageal squamous cell carcinoma. Conclusions: Abnormal pRB expression appears to be closely associated with tumor development. However, the existence of tumors with hyper-phosphorylat ed RE protein (inactivated form) in pRB-positive tumors, such as those in t he present study, should be considered. Thus, discrimination of this hyperp hosphorylated form of RE protein from the unphosphorylated RE protein is ne eded. (C) 2000 Wiley-Liss, Inc.