Results of radiosurgery in the management of recurrent and residual medulloblastoma.

Between June 1989 and January 1994, 14 patients with recurrent (n = 11) or posttreatment residual (n = 3) medulloblastoma were enrolled in a program to evaluate the efficacy and toxicity of stereotactic radiosurgery (SR). Initial treatment consisted of subtotal surgical resection in 12 patients and complete surgical resection in 2. Thirteen patients received systemic chemotherapy, and all had craniospinal irradiation prior to SR. SR was used as a technique for boosting sites of posttreatment residual disease in 3 patients (3 tumors) and as salvage therapy in 11 patients (14 tumors) with radiographically well-defined, discrete recurrent tumors. Patients underwent SR 1-97 (median 20) months after completing craniospinal irradiation. The median minimum peripheral tumor dose was 12 Gy. The median tumor volume at the time of SR was 6.9 cm3. With a median follow-up period from diagnosis of 27 (range 8-39) months, all patients treated with SR as a boost to sites of residual disease are alive without evidence of disease. In contrast, 6 of 11 patients who underwent SR for treatment of recurrent disease have died of progressive medulloblastoma. The median survival from the time of SR for patients treated for recurrent disease was 10 (range 5-59+) months. The predominant site of failure after SR was distant within the central nervous system, with 6 patients (43%) failing outside the posterior fossa. No patient failed locally within the radiosurgical target volume. Two patients (14%) developed marginal recurrences.(ABSTRACT TRUNCATED AT 250 WORDS)