STEREOTAXIC EXTERNAL-BEAM IRRADIATION IN PREVIOUSLY UNTREATED BRAIN-TUMORS IN CHILDREN AND ADOLESCENTS

Stereotactically guided external beam irradiation may be a useful form of treatment for small, well-circumscribed, but surgically inaccessible, primary brain tumors that are either benign or of low malignant potential. Between March 1988 and December 1991, 10 children and adolescents with previously untreated primary brain tumors were treated with stereotactic external beam irradiation (SEBI) using a linac-based dynamic technique. Eleven lesions were treated in the 10 patients. Treatment was given using a collimator diameter of 1.5-4 cm (median 2 cm). Single fractions of 18, 20, and 25 Gy were used for 3 lesions in 2 patients. A fractionated schedule delivering a median dose of 42 Gy in 6 fractions over 2 weeks was used in the remaining 8 patients. Morbidity related to treatment was minimal. Three patients suffered a temporary worsening of preexisting neurological symptoms and/or signs at 2, 5, and 5 months posttreatment, with subsequent recovery in all. With a median follow up post-SEBI of 17.5 months (range 5-47 months), improvement in neurological findings related to the lesion was noted for 5 treated lesions; 6 remained clinically stable. Seven of the 11 treated lesions improved radiologically, and only 2 showed evidence of progressive disease. Stereotactic external beam irradiation represents a potentially valuable therapeutic option for selected primary brain tumors in the pediatric and adolescent age group. Morbidity related to the treatment appears acceptable in frequency and type, and preliminary data with regard to response are encouraging. However, in order to assess the impact of such treatment on long-term tumor control and survival, further experience with a larger cohort of patients followed for a longer period of time will be necessary. (C) 1994 Wiley-Liss, Inc.