A study on molecular subtype of breast carcinoma using ER, HER2, PR, and its relation with Ki67

Using molecular biomarkers of breast cancer (BC) receives optimal treatment. Established biomarkers like estrogen receptor (ER), progesterone receptor (PR), HER2, and Ki67 may play significant roles in the sub-categorization of BC to predict the prognosis and specific therapy for each patient.This study aims to characterize breast carcinoma using molecular markers (ER, PR, and HER2 neu), identify their sub-types, and attain its relation with Ki67.

This cross-sectional (retrospective) study was conducted over four years at the Department of Pathology, SVS Medical College, Mahabubnagar, from April 2018 to March 2022. Fifty diagnosed cases of breast carcinomas were subjected to routine staining and immunohistochemistry (IHC) with ER, PR, HER 2 neu, and Ki67 using tissue microarray and classified into molecular subtypes.

In this study, 32% of participants were in the 50-59 age group. The right breast was involved in 52% of participants. The central quadrant was involved in 44%, UOQ 32%, UIQ 16%, and LOQ 8%. Moderately differentiated tumors exist in 40%, poorly differentiated in 36%, and well-differentiated in 24%. 84% of patients were ER-positive, 70% were PR-positive, and 72% were HER2/neu-positive. 28% of patients with positive Ki-67 were grade I, 22% were grade II, and 50% were grade III. Her2/neu contributed to 12% and triple-negative BC seen in 4%. The association between the ER status and Ki-67 positivity status is not statistically significant, with a P-value of 0.13. The association between the PR status and Ki-67 positivity status is statistically significant, with a P-value of 0.002. The association between the Her2/neu status and Ki-67 positivity status is also statistically significant, with a P-value of <0.0001.

Most cases were Ki67 positive and HER2 neu positive. Triple-negative cases showed a high Ki67 index. Ki67 plays a pivotal role in making treatment decisions. The Ki67 index is independent and can be used independently without being correlated with other indices, and Ki67 should be evaluated routinely in breast carcinoma cases.