Paradoxically to the well‐characterized role of RANK signaling as a mediator of progesterone in healthy breast or preneoplasic lesions (Gonzalez‐Suarez et al, 2010; Schramek et al, 2010), our results demonstrate that RANK predicts poor prognosis in ER− postmenopausal BC. This evidence concerns the gene TNFRSF11A and breast cancer.