Ki67 Protein expression and correlation with the histological grade and pTNM stage of colorectal carcinoma

: Colorectal cancer, is third most frequently encountered malignancy worldwide. Histological grade, stage, and proliferative index act as vital prognostic markers, playing a decisive role in patient care and prognosis. While histopathological examination can determine grade and stage, Ki67 protein expression by immunohistochemistry represents the proliferative capacity of the malignant cell population. : This Study was conducted to immunohistochemically analyze expression of Ki67 protein and its change with respect to different grades and stage of colorectal adenocarcinoma. : A total of 66 histologically diagnosed cases of colorectal carcinoma underwent histopathological examination followed by immunohistochemistry for Ki67 protein. : A statistically significant (p=0.04) correlation was obtained between Ki67 labelling index and histopathological grade, with higher values of Ki67 labelling index in poorly differentiated carcinomas (43.2±1.7). The Ki67 labelling index value was lowest in stage IV disease (11.4±2.4) with metastatic burden, with higher values in lower stage diseases, however this correlation was not found to be significant statistically (p=0.07). : The rate of cell division and proliferation measured by Ki-67 antibody is related to histological grade of the malignancy, demonstrating higher mitotic activity with loss of differentiation and anaplasia. Stage IV disease have lower mitotic activity, thus may be less amenable to cytostatic chemotherapy drugs, and require multimodality treatment with addition of radiotherapy and other drug regimes.