Femoral neck fracture following groin irradiation

Purpose: The incidence and risk factors are evaluated for femoral rneck fracture following groin irradiation for gynecologic malignancies. Methods and Materials: The radiation therapy records of 1313 patients with advanced and recurrent cancer of the vagina, vulva, cervix, and endometrium, treated at the mallinckrodt Institute of Radiology from 1954 to 1992, were reviewed. Median follow-up was 12.7 years. From this group, 207 patients were identified who received irradiation to the pelvis and groins with anterposterior-posterior anterior (AP-PA), 18 MV photons. Data were reviewed regarding irradiation dose to the fermoral neck and other presumed risk factors including age, primary site, stage, groin node status, menopausal status, estrogen use, cigarette use, alcohol consumption, adn osteoporosis. Results: The per-patient incidence of fermoral neck fracture was 4.8% (10 out of 207). Four patients developed bilateral fractures. However, the cumulative actuarial incidence of fracture was 11% at 5 years and 15% at 10 years. Cox multivariate analysis of age, weight, and irradiation dose showed that only irradiation dose may be important to developing fracture. Step-wise logistic regression of presumed prognostic factors revealed that only cigarette use and x-ray evidence of osteoporosis prior to irradiation treatment were predictive of fracture. Conclusion: Femoral head fracture is a common complication of groin irradiation for gynecologic malignancies. Fractrue in our database appears to be related to irradiation dose, cigarette use, and x-ray evidence of osteoporosis. Special should be given in treatment planning (i.e., shielding of femoral head/neck and use of appropriate electron beam energies for a portion of treatment) to the incidence of this complication.