Megavoltage radiation therapy for axial and inoperable giant-cell tumor of bone.

Background: Treatment of giant-cell tumor of bone generally involves wide en bloc resection of the lesion and the surrounding bone or curettage with or without bone-grafting or the use of cement. Radiation therapy has been used for patients who cannot be operated on for medical reasons or who have a tumor that is technically difficult to resect or that cannot be resected because of its location. We performed the present study to evaluate the efficacy of megavoltage radiation in terms of lack of tumor progression and treatment-related morbidity. Methods: Twenty patients who had giant-cell tumor of bone were managed with a single course of megavoltage radiation (forty to seventy gray administered at 1.8 to 2.0 gray per fraction with an average total duration of treatment of five to seven weeks) between March 1973 and March 1992. We used megavoltage photons, 160-megaelectron-volt proton beams, or a combination of the two. Results: After a median duration of follow-up of 9.3 years, the tumor had not progressed in seventeen of the twenty patients. Thus, the actuarial ten-year rate for lack of progression was 85 percent. Local regrowth was evident in one patient who had received radiation alone and in two of the thirteen patients who had been managed with partial resection and radiation. Operative treatment was successful in the three patients in whom the radiation treatment had failed. No radiation-induced tumors were observed in our series. Conclusions: We concluded that giant-cell tumor of bone was effectively treated with megavoltage radiation in our series of twenty patients in whom operative resection would have been difficult or was not feasible. The rate of tumors that did not progress with this regimen of radiation is similar to that reported by investigators from several other centers. Furthermore, these results closely rival those obtained with modern curettage procedures. Malignant sarcomatous transformation was not observed in our series. A longer duration of follow-up of a larger group of patients is necessary to provide a better estimate of the risk of malignant transformation.