Outcomes of single versus double hormone receptor–positive breast cancer. A GEICAM/9906 sub-study

Abstract Background Retrospective data suggest better outcomes for patients with double hormonal receptor (oestrogen [ER] and progesterone receptor [PgR])–positive (dHR+) early breast cancer, compared with single hormonal receptor–positive, sHR+, (ER+/PgR– or ER–/PgR+) disease. Here, we evaluate the classification according to intrinsic subtypes and clinical outcomes of sHR+ versus dHR+ in HER2-negative breast cancer patients enrolled in GEICAM/9906 study ( NCT00129922 ). Methods Archival tumours were retrieved retrospectively for the analysis of ER, PgR and HER2 status and classified into intrinsic subtypes using the PAM50 gene expression assay. Disease-free survival (DFS) and overall surv…