Asten KV, et al. - In estrogen receptor-positive (ER+), human epidermal growth factor receptor 2 (HER-2) negative breast cancers, experts assessed the prognostic value of progesterone receptor (PR) by tumor grade in two independent datasets. In luminal B-like vs luminal A-like breast cancer, findings suggested the probability of PR positivity to be more protective against metastatic relapse, but no strong conclusions can be made. In absolute risk, results suggested a greater clinical importance of an absent PR compared with low proliferative ER+ HER-2 negative tumors.