Study of immunohistochemical profile and molecular classification of breast carcinoma cases in a tertiary care hospital

Abstract

Breast cancers are a group of diseases with specific clinical, histological and molecular characteristics. Traditional classifications use histomorphological features to classify tumors into separate categories with differing behaviour and prognosis, which has certain limitations especially with regards to treatment. Molecular classification is useful to categorize the breast carcinoma cases for a definitive individualised treatment. The aim of this study is to establish the immunohistochemical profile of breast cancer cases and to estimate the prevalence of the molecular subtypes in a tertiary care hospital. This is a descriptive study where 57 breast carcinoma cases diagnosed over a period of 2 years from January 2017 to December 2018 at Saveetha Medical College and Hospital, were reviewed, histologically graded, staged and molecularly subtyped using relevant immunohistochemical markers. Correlations between the various molecular subtypes and their clinicopathologic features were evaluated by statistical methods. In this study, the average age was 53 years with peak incidence seen in 5 th and 6 th decades of life and stage II was most common with predominant histologic type being Invasive ductal carcinoma, not otherwise specified. Hormone receptors were positive in 28 cases (49.1%). Of these, 20 cases (35%) showed both estrogen receptor (ER) and progesterone receptor (PR) positivity, 5 cases (8.8%) showed only ER positivity, and 3 cases (5.3%) showed only PR positivity. On the basis of immunostaining for Hormone receptors, HER2 and Ki67, these cases were further classified into various molecular subtypes wherein Luminal A molecular subtype was found to be the most common (35.1%), followed Chander et al (2020): Immunohistochemical profile and molecular classification of breast cancer Dec, 2020 Vol. 23 Issue 23 Annals of Tropical Medicine & Public Health http://doi.org/10.36295/ASRO.2020.2323132 by HER2 (28.1%) and Triple negative (24.5%). Immunohistochemistry can be easily used as a surrogate tool to molecularly classify the breast carcinomas. Identification of the molecular subtypes is important for treatment planning and targeted therapy.