Prognostic Impact Of Androgen Receptor (Ar) And Forkhead Box A1 (Foxa1) In Early Her2-Negative Primary Breast Cancer: A Translational Substudy Of The Prospective Phase Iii Wsg-Planb-Trial.

557Background: AR and FOXA1 have been associated with better prognosis and may play a role as molecular targets in early breast cancer (EBC). This analysis presents the largest dataset of a prospective Phase III study analyzing the prognostic impact of AR and FOXA1: WSG PlanB recruited 3198 patients with HER2-negative EBC (2009-11). Patients with HR+/HER2-, pN0-1 EBC and RSu003c11 were recommended to omit chemotherapy; 2448 patients were randomized for an anthracycline-taxane-based therapy (4xEC-4xDoc) vs. an anthracycline-free regimen (6xTC). Methods: Tumor samples were analyzed centrally for ER, PR, Ki67 (cut-off 20% for Luminal-B-like EBC), and histological grade. AR and FOXA1 were assessed on tissue microarrays according to the immunoreactive score (IRS), which utilizes proportion of tumor cells expressing AR (or FOXA1) and intensity of staining. An IRS score of 3 or more was considered as positive. Univariate Cox analysis was performed to evaluate the association between AR, FOXA1, AR+/FOXA1+ and event-f...