Correlation of proliferative marker(Ki67), p53 expression and histomorphology in Colorectal carcinoma

Aim: To investigate combined immune-expression of Ki67 and p53 proteins in colorectal carcinoma and to correlate expression patterns of these markers with histopathological variables of colorectal carcinoma. Material and Methods: We determined immunohistochemical expression of proliferative expression of Ki67 and p53 in 47 cases of colorectal carcinoma in our set up. Results: Mean Ki67 index in our study was 34.7%. Mean Ki67 index of Adenocarcinoma NOS was observed to be 38.2%, which was higher than that of mucinous adenocarcinoma (28.3%) and signet ring cell carcinoma (11%). Mean Ki67 increased with dedifferentiation of tumor (Grade I-22.5%, Grade II-34.3%, Grade III-74.6%). p53 positivity rate was 72.3%. p53 positivity rate was higher in Adenocarcinoma NOS (72.9%) as compared to mucinous adenocarcinoma(57%). Percentage of diffuse p53 positivity increased with dedifferentiation of tumor. All cases of signet ring cell carcinoma showed diffuse p53 positivity. Correlation between Ki67 and p53 expression was not significant statistically. Conclusion: Mean Ki67 labelling index correlated with histological grade of colorectal carcinoma but not the histological type of tumor. p53 positivity rate did not correlate with histological grade nor the histological type. The combined expression of Ki67 and p53 in colorectal carcinomas did not correlate in the present study.