KI67/BCL2 index in invasive breast carcinoma (NST)

Abstract

Background: B-cell lymphoma-2 (BCL2) is an anti-apoptotic protein that has an anti-proliferative effect and is a favourable prognostic marker in breast carcinoma. Ki67/BCL2 ratio is emerging as a superior prognostic marker than either marker alone. Aim: This study investigated the association of Ki67/Bcl2 index with hormonal receptor status and other clinicopathological parameters in premenopausal and postmenopausal primary invasive breast carcinomas (NST). Method: Clinicopathological data were obtained from 63 (42%) premenopausal and 87 (58%) postmenopausal carcinomas from a prospective study. Immunohistochemical assessment of ER, PR (Allred score), HER2 (ASCO/CAP 2013), Ki67 and BCL2 in the tumours were performed using routine protocols. BCL2 and Ki67 scores were obtained based on the percentage of positively stained cells (0=0–10%, 1=11–32%, 2=>33%). BCL2 staining score was subtracted from the Ki67 score to produce five categories (−2, −1, 0, 1, 2) and further categorised into two groups, low-index (-2, -1, 0) and high-index (1, 2). Association of Ki67/Bcl2 index with tumour grade, tumour size, T and N stage, nodal status, node ratio (<0.15), ER, PR and HER2 status and molecular subtype, were evaluated using the Chi-square test (SPSS-20). Associations were considered significant when p≤0.05. Results and conclusion: High Ki67/BCL2 index was significantly associated with negative ER (premenopausal χ2=4.701(1), p=0.030; postmenopausal χ2=23.104(1), p≤0.001) and negative PR (premenopausal χ2=12.106(1), p=0.001; postmenopausal χ2=12.956(1), p≤0.001) expression in both groups. It was also significantly associated with premenopausal grade ΙΙΙ tumours (χ2=8.168(2), p=0.017) and postmenopausal triple negative breast cancers (χ2=19.510(4), p=0.001). It is evident that high Ki67/BCL2 index, indicating a high proliferation rate, is associated with poor prognosticators in breast carcinoma and is suggestive of a poor clinical outcome.