How would you approach adjuvant therapy for a post-menopausal women with cT2 cN0 TNBC on biopsy s/p neoadjuvant chemotherapy and mastectomy who is later found to have RCB2 HR+ breast cancer on surgical pathology?

First, is she BRCA positive? If so, there is a role for olaparib in adjuvant setting (OlympiA trial). I would treat with capecitabine as per the CREATE X trial (Masuda et al., PMID 28564564). Although the subset of triple negative cancers benefited most, and the point estimate for the ER or PR positive cohort (about 2/3 of patients enrolled) crossed 1, in this case, the ER was only 34% and PR was 0%. I also would treat her with an AI, and if the Ki-67 was 20% or more, add abemiciclib. The question of whether you should do concurrent or sequential capecitabine with AI is an unanswered question. I would do sequential because I never mix chemotherapy with endocrine therapy out of habit, not data.