TNFRSF11A and breast cancer: Besides bisphosphonates modern therapies such as directed antibody therapy against RANKL (receptor activator of NF-κB ligand) with denosumab [2] are in the focus of current research efforts as the RANK (receptor activator of NF-κB) pathway has been described to be involved in both bone metabolism and breast cancer pathogenesis and progression [3–9].