Surprising progress has been made in the biology of breast cancer in recent years. Breast cancer is the commonest cancer in women worldwide. In India it is the second most common female malignancy , accounting 28% of all malignancies in women. The age standardized rate is 54.9 per 1,00,000 per year. Biomarkers expression in breast cancer is used as a prognostic indicator and predictor of response to hormonal and chemotherapy. To date, the leading parameters that guide therapy in breast cancer are estrogen receptor (ER), progesterone receptor (PR) and human epidermal growth factor (HER2neu). In recent years, gene expression analysis studies have demonstrated the vitality of proliferation signatures not only in the prognosis of breast cancer but also as a predictive response to subsequent therapy ,(3,4,5 ). The aim of the current study is to analyse the correlation between various pathological prognostic markers of Invasive ductal carcinoma (IDC) of the breast with Ki67 index and provide a rough estimate of the cut-off values for the latter. The methodology used is formalin fixed paraffin embedded tissue blocks and slides (H&E histology and Immunohistochemistry) were retrieved and reviewed. Re-cutting and re-staining of faded material were carried out when needed. This is a two-year study from February 2015 to February 2017. Data were analysed using “SPSS Version 23.” The outcomes of biomarker analysis showed that immunohistochemical expression of Ki67 appears to be associated with absence of ER, PR expression and Her2neu positivity. These findings underlined the relationship between Ki67, a relatively new biological marker which is a valuable predictive factor in invasive ductal carcinomas of breast. index” and the (p =0.04), PR and Ki 67 (p=0.026). A slightly higher incidence of Her-2/neu positivity was seen, and there was a significant connection between “HER2-Neu” and “Ki-67” index and the (p =0.029). The molecular groups and Ki67 have no discernible relationship.

Keywords : Ki-67, Prognostic Markers, Invasive Ductal Carcinoma, Breast Cancer