Fracture Risk in Older, Long-Term Survivors of Early-Stage Breast Cancer

Objectives To examine the effect of breast cancer and its treatment on fracture risk in older breast cancer survivors. Design A 10‐year prospective cohort study beginning 5 years after a diagnosis of breast cancer for survivors and match date for comparison women. Setting Six integrated healthcare systems. Participants Women aged 65 and older (1,286 survivors, 1,286 comparison women, mean age 77.7 in both groups, white, non‐Hispanic: survivors, 81.6%; comparison women, 85.2%) who were alive and recurrence free 5 years after a diagnosis of early‐stage breast cancer and matched on age, study site, and enrollment year to a comparison cohort without breast cancer. Measurements Cox proportional hazards models were used to estimate the association between fracture risk and survivor‐comparison status, adjusting for drugs and risk factors associated with bone health. A subanalysis was used to evaluate the association between tamoxifen exposure and fracture risk. Results No difference was observed in fracture rates between groups (hazard ratio (HR) = 1.1, 95% confidence interval (CI) = 0.9–1.3). The protective effect of tamoxifen was not statistically significant (HR = 0.9, 95% CI = 0.6–1.2). Conclusion Long‐term survivors of early‐stage breast cancer diagnosed at age 65 and older are not at greater risk of osteoporotic fractures than age‐matched women without breast cancer. There appears to be no long‐term protection from fractures with tamoxifen use.