Competing risks of mortality by PAM50 intrinsic subtype: BC tamoxifen-treated cohort.

Abstract

562 Background: We previously showed that baseline patient/tumour characteristics, or prior treatment affected cause of death in NCIC CTG endocrine therapy trials (MA.14, MA.17, MA.27), in particular older age was associated with non-breast cancer death. We now examine whether PAM50 intrinsic subtypes were differentially associated with cause of death in a cohort of British Columbia tamoxifen-treated patients. Methods: Patients were 718 post-menopausal women, treated with tamoxifen, without adjuvant chemotherapy who had tumours which were Luminal A, Luminal B, Basal, or HER2 intrinsic subtype and known cause of death [cancer-specific (BrCa); other cause (OC)]. We tested whether intrinsic subtype and other patient and tumour characteristics were associated with 1) all cause mortality, and if so, 2) cause-specific mortality. We also fit step-wise forward cause-specific adjusted models. Results: Patients were followed a median of 11.7 years. In women <70 years of age, 138/425 (32% died of breast cancer) and ...