Long-Term Risk of Hip Complications After Radiation Therapy for Prostate Cancer: A Dose-Response Study
Elisabeth Rasmusson, Per Nilsson, Elisabeth Kjellén, Adalsteinn Gunnlaugsson
Abstract
PURPOSE: The aim of the present study was to analyze the long-term incidence of hip complications after external beam radiation therapy compared with age-matched controls from the general population. We also investigated whether there were any dose-response associations. METHODS AND MATERIALS: A total of 349 patients with prostate cancer treated to curative dose with external beam radiation therapy between 1997 and 2002 were included in the study. Physical and fractionation-corrected dose-volume descriptors were derived for the femoral heads, pubic bone, and sacrum. Information on skeletal events was collected for the patients and 1661 matched controls through the Prostate Cancer database Sweden. Uni- and multivariable Cox proportional hazard regressions were used to analyze the time to event. RESULTS: = .02). The cumulative incidence of osteoarthritis at 10 years was 8.1% and 4.9% in the irradiated cohort and the controls, respectively. A significant relationship between osteoarthritis and the volume of the femoral head receiving ≥40 Gy (ie, EQD2) was found. CONCLUSIONS: In this study of 346 patients treated with conventional radiation therapy, we found no increased risk of hip fracture but an increased risk of clinically relevant osteoarthritis at long-term follow up. Our results indicate a dose-response relationship between osteoarthritis and the volume of the femoral head receiving an EQD2 dose of ≥40 Gy.