Bone Fractures and Incident Epithelial Ovarian Cancer in a Prospective Cohort Study

Abstract

Osteoporosis and osteoporotic fractures are hypothesized to reflect circulating hormone levels in older women and have been inversely associated with breast and endometrial cancers. However, associations between fractures and ovarian cancer, another hormonal cancer, have not been examined. Therefore, we conducted a prospective study among women in the Breast Cancer Detection Demonstration Project Follow-up Study. Fractures after age 45 were assessed using two questionnaires from 1987 to 1995. Relative risks (RRs) and 95% confidence intervals (CIs) were estimated by Cox proportional hazards models, adjusting for potential confounders. Fracture location was used to further evaluate the fractures most likely to be osteoporotic. Among 36,115 women with up to 11 years of follow-up (average follow-up was 8.3 years), there were 151 cases of incident ovarian cancer. Fractures were reported by 19% (n = 6,919) of women. Ovarian cancer risk was not associated with any (RR = 1.13, 95% CI 0.74-1.71) or likely osteoporotic (RR = 1.05, 95% CI 0.65-1.69) fractures. Among never users of postmenopausal hormones, the association between any fracture and ovarian cancer (RR = 1.21, 95% CI 0.55-2.65, n = 50 cases) also was statistically nonsignificant. Data from this large, prospective study do not support an association between fractures and ovarian cancer risk.