A study of expression of BCL-2 in colorectal carcinoma with histopathological correlation

Introduction: Colorectal cancer is the major cause of mortality and morbidity worldwide. Incidence in males - 4.3 /1, 00,000, in females - 3.4/1,00,000. The etiology of colorectal cancer is complex, involving interplay of environmental and genetic factors. Colorectal cancers have been reported to show BCL-2 over expression although, in comparison with adenomas, there is lower intensity of expression in the invasive tumors. There may also be a loss of expression with loss of tumor differentiation and it would appear that the role of BCL-2 is probably more important in the early development of colorectal tumors than in later tumor progression. Aim and objectives: To perform and interpret BCL-2 immunostaining on all diagnosed colorectal carcinomas, to infer the rate of positivity and negativity of the BCL-2 expression in the colorectal lesions, to correlate the BCL-2 expression with the grades of the colorectal carcinomas, to indicate the prognostic value of BCL-2 expression in colorectal carcinomas. Materials and methods: A present study was done in MGM Hospital, Warangal for duration of 5 years. A total of 64 cases were studied. All colorectal carcinoma cases are subjected to BCL-2 immunostaining. Results: In present study, the commonest age group were from 60-69 years with majority of the lesions diagnosed as adenocarcinomas. Males contributed to large number of cases (33) and rectum is the most common site in the present study. Majority of cases (40.6%) in this study were well differentiated carcinomas. BCL-2 overexpression was seen in 42(65.6%) cases, majority were colorectal adenocarcinomas. 96.2% of well differentiated, 75% of moderately differentiated adenocarcinomas and 10% of poorly differentiated adenocarcinomas showed overexpression of BCL-2 and 12.5% of mucinous carcinomas showed BCL-2 positivity. There was a significant correlation between grade and BCL-2 expression. Higher scores were seen in well to moderately differentiated carcinoma than poorly differentiated carcinoma. In well differentiated carcinoma, 19 cases showed score 3 and in moderately differentiated carcinoma, 5 cases showed score 3 which contained strong BCL-2 expression. In poorly differentiated carcinoma, majority (9 cases) were score 0 and in mucinous carcinoma as well, 69 majority (7 cases) were score 0 which contains negative BCL-2 expression. In rectal cancers BCL-2 overexpression was more common that colon cancers. Rectum shows 47% positivity and left colon 36%. Thus in present study rectal cancers showed high BCL-2 expression. Males (23 cases) showed higher BCL-2 expression than females (20 cases). Conclusion: There is a significant correlation (P<0.00001) between BCL-2 over expression and grade of colorectal adenocarcinoma, but there is no significant correlation is observed with variables like age, gender, tumor location. BCL-2 over expression serves as good prognostic marker in colorectal adenocarcinomas and it will help to assess the responsiveness of patients to standard treatment.