In the Tromsø study by Vik et al., serum samples from 76 subjects in Norway that developed breast cancer were categorized into tertiles for serum levels of OPG: 0.46–2.78 ng/mL, 2.79–3.55 ng/mL, and 3.56–25.81 ng/mL, respectively [32]. Here, TNFRSF11B is linked to breast cancer.