Long-term pelvic fracture and overall mortality risk after pelvic cancer and pelvic radiation

Background: The association of pelvic radiation with pelvic fracture risk has not been examined in prospective cohort settings with comprehensive fracture risk assessment, cancer-free comparison populations, and long-term follow-up. Our objective is to better characterize pelvic fracture and overall mortality risks in postmenopausal women participating in the Women's Health Initiative. Methods: A total of 135743 Women's Health Initiative participants aged 50 to 79 years enrolled from 40 US clinical centers from 1993 to 1998 who had entry Fracture Risk Assessment Tool scores were eligible. Outcomes included pelvic cancer diagnosis, pelvic fracture occurrence, and mortality. Cox proportional hazards regression models were used to examine associations of pelvic cancer and pelvic radiation with pelvic fracture and mortality risk. Results: After 17.7 years (median) follow-up, 4451 pelvic cancers, 10139 pelvic fractures, and 33040 deaths occurred. In multivariable analyses, women with incident pelvic cancer, compared with women who remained pelvic cancer free, had higher pelvic fracture risk (hazard ratio [HR] = 1.26, 95% confidence interval [CI] = 1.11 to 1.43) and higher overall mortality risk (HR = 2.91, 95% CI = 2.77 to 3.05). Women with pelvic cancer treated with pelvic radiation, compared with women with pelvic cancer not treated with pelvic radiation, had higher pelvic fracture risk (HR = 1.98, 95% CI = 1.41 to 2.78) and higher overall mortality after pelvic cancer (HR = 1.32, 95% CI = 1.15 to 1.52). Conclusions: Postmenopausal women with pelvic cancer, especially those receiving pelvic radiation, are at higher pelvic fracture risk and higher overall mortality risk. As therapeutic advances have reduced cancer mortality, attention to and interventions for pelvic fracture prevention may be important in pelvic cancer survivors.