Immunohistochemical Expression of p53 and bcl-2 in Colorectal Adenomas and Carcinomas Using Automated Cellular Imaging System

Background & Objective: The current approaches to reduce the risk of colorectal carcinoma are through the detection and removal of the precursor lesion” adenomatous polyps”. The study was conducted to evaluate the immunohistochemical expression of p53 and bcl-2 in colorectal adenomas and carcinomas. Patients and Methods: A total of 86 cases, 33 colorectal adenomas, 33 colorectal adenocarcinomas and 20 samples of non -tumerous colonic tissue as control, were included in this retrospective study. Sections were stained immunohistochemically for p53 and bcl-2. Scoring was performed using Digimizer software. Data were analyzed using SPSS program (Statistical Package for Social Sciences) version 16 and Microsoft Office Excel 2007. Results: The frequency of p53 positive cases was significantly higher in carcinoma than adenoma while the frequency of bcl-2 positive cases was significantly higher in adenoma than carcinoma. p53 expression was significantly higher in large sized adenomas, villous configuration, severe dysplasia, and multiple lesions. Bcl-2 expression showed significantly correlated with adenomas of small size, solitary, tubular, and mild dysplasia. There was a significant correlation between bcl-2 expression and non-mucinous carcinoma and a negative correlation with tumor size. There was an inverse relationship between bcl-2 and p53 expression in both colorectal adenomas and carcinomas. Conclusion: p53 overexpression is a late event in colorectal tumorigenesis. bcl-2 may play an important role in the early stage of adenoma-carcinoma sequence.