Pelvic insufficiency fracture after pelvic radiotherapy for cervical cancer: analysis of risk factors.

PURPOSE: To investigate the incidence, clinical characteristics, and risk factors of pelvic insufficiency fracture (PIF) after pelvic radiotherapy (RT) in cervical cancer. METHODS AND MATERIALS: Medical records and imaging studies, including bone scintigraphy, CT, and MRI of 557 patients with cervical cancer who received whole-pelvic RT between January 1998 and August 2005 were reviewed.
RESULTS: Eighty-three patients were diagnosed as having PIF after pelvic RT. The 5-year cumulative incidence of PIF was 19.7%. The most commonly involved site was the sacroiliac joint. Pelvic pain developed in 48 patients (57.8%) at diagnosis. Eleven patients (13.3%) needed admission or narcotics because of severe pain, and others had good relief of symptoms with conservative management. In univariate analysis, age>or=55 years (p<0.001), anteroposterior/posteroanterior parallel opposing technique (p=0.001), curative treatment (p<0.001), and radiation dose>or=50.4 Gy (p=0.005) were the predisposing factors for development of PIF. Concurrent chemotherapy (p=0.78) was not significant. Multivariate analysis showed that age>or=55 years (p<0.001), body weight<55 kg (p=0.02), curative treatment (p=0.03), and radiation dose>or=50.4 Gy (p=0.04) were significant predisposing factors for development of PIF.
CONCLUSION: The development of PIF is not rare after pelvic RT. The use of multibeam arrangements to reduce the volume and dose of irradiated pelvic bone can be helpful to minimize the risk of fracture, especially in elderly women with low body weight.