Abstract: The last few years showed an increase in the incidence of the colorectal cancer in Egypt. Between 20% and 50% of patients with this cancer are susceptible to death within five years of diagnosis. Tumor growth results from a disturbance in the balance between the rates of cell proliferation and cell death (apoptosis). We studied the expressions of proteins involved in the regulations of apoptosis as possible factors responsible for uncontrolled growth in colorectal cancer

One hundred cases of colorectal carcinomas were immunohistochemically stained to detect bcl-2, bax, and p53 expression. In situ hybridization (using ApopTag) was performed to detect apoptotic bodies and computerized image analysis was done to semi-quantitate protein expression for each stain. Only 77% of carcinomas were positive for bcl-2 with high positivity in 39% of cases. However, 71% showed positive bax staining with strong positivity in 50% of cases. P53 exhibited positivity in 85% of cases with stong nuclear staining in 68% of cases. We found that apoptotic index was increased significantly in larger carcinoma. P53 CH was higher in right side colon cancer than left. Bcl-2 expression was decreased progressively with depth of the tumor invasion, whereas bax was increasing till reach serosa then start to decrease. There was negative bax LI and positive p53 MOD correlation with angiolymphatic invasion of carcinoma. P53 LI and MOD were significantly lower in carcinomas with lymph node metastasis

The above results suggest that decreased bcl-2 expression is a good indicator of tumor invasion through the wall of the colon, whereas decreased p53 is a good indicator of tumor invasion outside the wall and/or tumor metastasis. Higher bcl-2 LI, bax MOD and p53 LI and MOD are associated with better survival in colorectal cancer patents