TNFRSF11B and breast cancer: Briefly, a prospective study conducted by Vik et al. showed when stratified by age and sex, a significant inverse relationship between serum OPG and breast cancer risk in women under 60 years of age, but not in women above 60 years of age after adjustment, although the sample size was relatively small (upper vs. lower tertile RR = 0.24; 95% CI 0.10–0.61; ptrend = 0.002) [39].