Bcl-2 expression in colorectal carcinoma and its correlation with clinicopathological parameters

Background: Bcl-2 gene is a 26-kD protein that blocks apoptosis and inhibits programmed cell death. Its mutation is frequently detected genetic alteration, in human cancers. Its expression can easily be detected by immunohistochemistry (IHC). Objective: The objective was to estimate the frequency of Bcl-2 expression in colorectal carcinoma and its correlation with clinicopathologic parameters. Materials and Methods: The overexpression of Bcl-2 was studied in 112 paraffin-preserved colorectal carcinoma samples using E-17 clone antibody; Biogenex. The number of cells stained was scored semiquantitatively as none (no immunoreactive cells detectable), weak (1+, <5%), moderate (2++, 5%–50%), and intense (3+++, >50%). All tumors showing Bcl-2 immunoreactivity (at least +) were considered positive. The correlation between Bcl-2 protein expression and clinicopathological parameters was evaluated using Chi-square analysis. Results: Bcl-2 staining was positive in 45 of 112 cases. Of these, 15 cases were weak positive (score 1), 17 cases were moderately positive (score 2), and 13 cases were intensely positive (score 3) for Bcl-2 protein expression. Sixty-seven cases were negative for Bcl-2 staining (score 0). There was statistically significant correlation between Bcl-2 staining and sex (49% of females expressed Bcl-2 in tumors; P = −0.04), pathological type (mucinous vs. nonmucinous; P = −0.02), and tumor stage (P = −0.04). There was no significant correlation between Bcl-2 staining and age (P = −0.38), site of tumor (left colon vs. right colon; P = −0.13), pathological differentiation (P = −0.73), and between Bcl-2 scoring and tumor differentiation (P = −0.91). Conclusion: Bcl-2 protein seems to play an important role in the carcinogenesis of colorectal cancer. Considering the acceptable reliability and feasibility of IHC method for the detection of Bcl-2 immunoreactivity, this technique may be expected to serve as an important diagnostic and prognostic marker in colorectal carcinoma.