TNFRSF11B and breast cancer: Thirty cases of breast cancer were reported in the 1st Tertile of OPG serum group (0.46–2.78 ng/ml), 26 breast cancer cases for the 2nd Tertile of OPG serum group (2.79–3.55 ng/ml) and 20 breast cancer cases for the 3rd Tertile of OPG serum group (3.56–25.81 ng/ml).