BRCA1 associated breast cancers are frequently positive for ER and its cytoplasmic expression confers a poor prognosis

Abstract

Aim It is recognised that oestrogens mediate their key role in the development and progression of breast cancer through two transcription factors, oestrogen receptor alpha (ERα) and oestrogen receptor beta (ERβ). ERα has been studied extensively in familial breast cancers but there are limited data on ERβ. Here, we present a larger study looking at the impact of ERβ expression on clinical outcome and on different molecular subtypes of familial breast cancer. Methods Immunohistochemical study of ERβ in a cohort of 139 familial breast carcinomas as tissue microarray was done and compared with a cohort of 186 sporadic cancers collected. Sections were stained with mouse ERβ monoclonal antibody 14C8 (Abcam). Results A significant proportion of BRCA1 and basal-like familial breast carcinomas that are ERα negative, express ERβ. High cytoplasmic ERβ expression in familial basal-like cancers was significantly associated with shorter overall survival, but not relapse free survival. Conclusion Currently therapeutic and prognostic targets for breast cancer are exclusively dependent on the presence of the ERα. We propose, ERβ should be assessed and tamoxifen or other hormonal therapies should be considered in such patients that demonstrate ERβ positivity.