An institutional analysis of the correlation between KI 67 index and other prognostic markers in invasive breast cancer in northern province, Sri Lanka

Introduction: Breast cancer is the commonest cancer among females in Sri Lanka. The markers that define the treatment recommendations are Estrogen receptors (ER) status, Progesterone receptor (PR) status, HER-2 neu and Ki-67 proliferative index.

Methodology: This is a retrospective study performed on the pathological specimens of invasive ductal carcinoma at Teaching Hospital Jaffna from January 2020 to July 2022. Ki-67 index above 20 was considered high and below 20 as low. The correlation between Ki-67 and other prognostic markers was analyzed as categorical variables using chi-square test.

Results: 143 specimens were analyzed, of which 101 were core biopsies and 42 were mastectomy/ WLE specimens. ER, PR and HER2/neu positivity were noted in 100 (69.9%), 85 (59.4%) and 41(28.7%) cases, respectively. Nottingham tumour grade 1,2 and 3 was noted in 16 (11.2%), 74 (51.7%) and 38 (26.6%) cases, respectively. The mean Ki-67 index was 40.21 %. High Ki-67 index was noted in 107(74.8%) and low in 36(25.2%) cases. A significant correlation was noted between ER, PR positivity and Ki-67 index (p=0.02, 0.01). The correlation between HER2/neu positivity and Ki-67 was insignificant (p=0.06). A significant correlation was found between the Ki-67 index and tumour grade (p=0.01).

Conclusion: This study showed that high Ki-67 expression is associated with high tumour grade, ER/PR positivity and HER2/neu negativity. Varying results with the published literature reveal geographical variations and warrant large-scale analysis with a bigger sample size.