ABSTRACT Pelvic fractures, especially hip fractures, are a major cause of illness and death in older women. Radiation therapy is known to cause bone damage and may increase the risk of fracture, but the risk associated with standard-course fractionation is insufficiently understood. This retrospective cohort study analyzed data from the Surveillance, Epidemiology, and End Results (SEER) cancer registry, linked to Medicare claims data, to learn whether women having pelvic radiotherapy for anal, cervical, and rectal cancers are at increased risk of pelvic fracture. The 6428 participants were women aged 65 and older whose pelvic malignancy was diagnosed in 1986–1999. The study population included 2855 women who received radiotherapy and 3573 who did not. The study women had an average age of 74.5 years and were followed up for 4.3 years on average. A total of 2449 women were followed for 5 years or longer after receiving a diagnosis of cancer. Pelvic fractures developed in 8.6% of women during follow up. Nine of 10 injuries were hip fractures. In addition, 5.4% of women had an arm or spinal fracture. For all 3 tumor types, the cumulative incidence of pelvic fractures was greater in women receiving radiotherapy. Using a proportional hazards model to control for other factors, radiotherapy remained a significant risk factor for pelvic fracture. Hazard ratios associated with radiotherapy were 3.16, 1.66, and 1.65, respectively, for women having anal, cervical, and rectal cancers. Blacks were at lower risk of fracture, but there was no statistically significant relationship between race and radiation therapy. Older women receiving radiotherapy for pelvic cancer should be aware of the risk of fracture and considered for preventive measures such as monitoring of bone mineral density, treatment to prevent osteoporosis, and strategies for preventing falls. In addition, it may be possible to alter methods of radiotherapy so as to minimize the dose to bone.
