EXPRESSION OF BRCA1 BY IMMUNOHISTOCHEMISTRY AND ITS ASSOCIATION WITH ER,PR, HER2NEU STATUS IN IDC OF BREAST

Abstract

BACKGROUND: Carcinoma of breast is a heterogeneous disease which differs in their clinical behaviours and responses to treatment and outcome. Prognosis in breast cancer depends on many factors such as histological grade, molecular type, size of the tumor, lymphnode status, Estrogen receptor (ER), Progesterone receptor(PR) and Human epidermal growth factor 2 status (Her2neu). The prevalence of breast carcinoma in India is rising recently. Etiopathogenesis of breast cancer comprises both genetic and non-genetic causes. Among the more than 300 genes which leads to breast cancer the tumor suppressor gene like BRCA1 plays a vital role not only in germline mutation but also sporadic cases. It has an autosomal dominant trait of inheritance.BRCA1 revealed a role in breast cancer as well as increased risk of developing epithelial ovarian cancer and male breast cancer etc. Hence detection of BRCA1 mutation helps in screening of high risk family members. AIMS: To evaluate the expression of BRCA1 in infiltrative Ductal carcinoma and to analyse the association of BRCA 1 with histopathological parameters and Estrogen Receptor, Progesterone Receptor and Human Epidermal Growth factor Receptor 2 neu expression. MATERIALS AND METHODS: This is a laboratory-based exploratory study. Data has been collected from the Department of Pathology, Sri Devaraj Urs Medical College, Tamaka, Kolar from October 2019– July 2021. Retrospective cases were collected from January 2019 to september2019.We have selected 56 infiltrative ductal carcinoma of breast cases and patients subjected to chemotherapy & radiotherapy, trucut biopsies and with incomplete patient details were excluded. H&E slides were reviewed. Immunostaining for BRCA1 was performed. Individual 18 clinicopathological parameters were compared with the BRCA1 mutation. p-value of <0.05 considered statistically significant. RESULTS: In our study among 56 cases 18 cases(32.1%) showed BRCA1 mutation. BRCA1 mutation were asscociated with postmenopausal age , larger tumorsize, lower tumor grade and higher tumor staging. When we analysed the biomarkers and BRCA1 mutation showed negative association with ER,PR and Her2 neu and high Ki67 proliferation index. Prognosis was done with the NPI and does not gave a significant result. Molecular subtyping showed 44.2% cases in luminal A type. CONCLUSION: Our study showed BRCA1mutation was expressed in 32.1% and associated with postmenopausal age group, larger tumor size and higher staging and negative hormonal status of breast carcinoma. More data is needed to look in to the clinical outcome of BRCA1 mutation with PARP inhibitor therapy.