Abstract PS6-55: The prognostic utility of AR/ER ratio in young women with breast cancer

Background: World over, less than a quarter of breast cancer diagnoses are in premenopausal women. However, in India premenopausal women constitute half of all women with breast cancer in most hospital case series. Most of these women present at advanced stages with aggressive subtypes of disease and hence the high mortality.The role and utility of detecting androgen receptor (AR) expression in the different sub-types of breast cancer, especially the ones without hormone receptor expression is yet to be firmly established. Evidence from previous studies is suggestive of its beneficial role in hormone receptor positive (HR+) breast cancer. The biological function of AR on the mammary epithelium is determined by the Estrogen receptor (ER) context, in that, it is found to be anti-proliferative in ER positive tumors while it is thought to promote growth in the absence of ER activity. An interesting approach to representing this interplay is as a ratio between AR/ER expressions. As expected, the ratio has been shown to be positively correlated with better outcomes in hormone receptor cancers, mostly in postmenopausal women. The effect of a high ratio in ER negative tumors seems more complicated. In this study, we have evaluated the AR/ER ratio specifically in patients younger than 50 years in whom the estrogenic influence is dominant due to their premenopausal status.Materials and Methods: Tumor samples from patients 50 years or younger were chosen from a larger cohort of 275 patients with median follow up of 72 months. Expression of ER and AR proteins were detected by immunohistochemistry (IHC), and the transcript levels of ESR1 and AR were determined by quantitative PCR. Relative normalized units of their gene expression were used to calculate the AR/ER ratio. A cut-off at the 3rd quartile was used to divide tumors into categories of high and low ratios. Clinical characteristics were compared between the low and high ratio groups along with IHC subtype distribution (HR+, HER2+ and Triple negative (TNBC)). Kaplan Meier curves was used for survival analysis and Cox proportional hazard analysis model was used to calculate the hazard ratio (HR). The results were validated in METABRIC dataset.Results: Eighty-eight (32%) patients were Citation Format: Jyothi S Prabhu, Aruna Korlimarla, Savitha Rajarajan, Annie Alexander, Ce Anupama, Rakesh Ramesh, Bs Srinath, T.S Sridhar. The prognostic utility of AR/ER ratio in young women with breast cancer [abstract]. In: Proceedings of the 2020 San Antonio Breast Cancer Virtual Symposium; 2020 Dec 8-11; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2021;81(4 Suppl):Abstract nr PS6-55.