A clinicopathologic study of Ki-67 proliferation index in colorectal carcinoma

OBJECTIVE: To investigate Ki-67 immunoexpressions in colorectal cancer and analyze possible correlations with variable clinicopathological prognostic factors.

METHODS: A cross-sectional study of tissue sections from 50 formalin-fixed and paraffin-embedded tumor specimens were examined at the Histopathology Laboratory of Rezgary Teaching Hospital in Erbil, Iraq between January 2010 and July 2011. Ki-67 labeling index is calculated immunohistochemically using the monoclonal antibody MIB-1, and the standard streptavidin-biotin immunoperoxidase method. The clinicopathologic and prognostic features were statistically analyzed.

RESULTS: Over-expression of Ki-67 proliferation protein was found in 31 (62%) cases. Statistical analyses revealed a significant relation between Ki-67 proliferation index and histologic type (p=0.005) and tumor grade (p=0.018); but no significant relation was calculated with the other clinicopathological parameters such as age, gender, tumor's size, site, depth, stage, nodal status, and vascular invasion (p>0.05).

CONCLUSION: Ki-67 immune overexpression is a frequent finding in our colorectal cancer cases; but it is not enough to monitor Ki-67 proliferation index alone for prognosis in colorectal cancer.