Pelvic insufficiency fractures in patients with cervical and endometrial cancer treated with postoperative pelvic radiation.

OBJECTIVE: There is an increased awareness of pelvic insufficiency fractures (PIF) as a potential morbidity of pelvic radiotherapy (RT). The purpose of this study was to determine the incidence of PIF and assess prognostic factors, including intensity-modulated RT (IMRT), in gynecologic oncology patients treated with postoperative pelvic RT.

METHODS: We performed a retrospective review of all patients with endometrial or cervical carcinoma who received postoperative pelvic RT at our institution during 2000-2008. Patients who received definitive or palliative RT were excluded.

RESULTS: A total of 222 patients were identified, of whom 11 (5%) developed PIF at a median time of 11.5months (range, 5.5-87.3months) from RT completion. The 5-year actuarial rate was 5.1% (95% CI 3.3-6.9). In patients with osteoporosis, the 5-year rate was 15.6% compared with 2.9% for those without (P=0.01). Similarly, patients who were on prior hormone-replacement therapy (HRT) had a higher rate (14.8% vs 4.1%, P=0.009). The median body-mass index (BMI) for patients who developed PIF was significantly lower than those who didn't (25.9 vs 27.2, P=0.016). The rate of PIF was 4.9% whether patients received IMRT or conventional RT.

CONCLUSIONS: The 5-year risk of PIF for postoperative pelvic RT in cervical and endometrial cancer is 5.1%. Women with history of osteoporosis, prior HRT, or low BMI need to be counseled about the risk of PIF. The use of IMRT did not decrease PIF, but further studies are needed to determine if a dose/volume relationship exists between RT and PIF.