TNFRSF11B and breast cancer: In women without known genetic predisposition, high receptor activator of NFκB ligand (RANKL)/OPG ratios were suggested indicative of breast cancer manifestation, and elevated RANKL and P4 serum levels stratified a subgroup of women at high risk of developing breast cancer 1–2 years before diagnosis (23), though recently a report rebutted plasma RANKL levels correlating with breast cancer risk in germline BRCA1/2 mutation carriers (24).