Immunohistochemical expression of Ki-67 and p53 in colorectal carcinoma

Objectives: To investigate the expression of Ki-67 and p53 in colorectal carcinomas and to correlate expression patterns of these markers with histopathological grades of colorectal carcinoma. Materials and methods: We determined immunohistochemically the expression of Ki-67 and p53 antibodies in 62 cases of colorectal adenocarcinomas. Results: Mean Ki-67 index in our study was 33.9%. Mean Ki-67 increased with dedifferentiation of tumor (Grade I-18.8%, Grade II-33.2%, Grade III-49.1%). The difference in mean Ki-67 index is statistically significant with histopathological grade. (p <0.001). p53 overexpression was seen in 69.3% cases. Percentage of diffuse p53 positivity increased with dedifferentiation of tumor. p53 positivity rate was observed in 22.2% cases of well differentiated carcinoma and increased from 76.2% to 81.8% in moderately to poorly differentiated carcinoma. However, the difference was statistically insignificant with histopathological grade. Conclusion: As the result of this study it is concluded that in colorectal carcinoma Ki-67 LI correlated with grade and increases with the dedifferentiation of tumor and also p53 over expression increases with dedifferentiation of tumour. Thus, the evaluations of expression of p53 and Ki-67 can be used as a poor prognostic marker allowing the identification of aggressive forms.