Radiation-induced tumors in children irradiated for brain tumor: a longitudinal study.

BACKGROUND: Radiation-induced tumors (RIT) are increasingly recognized as delayed complications of brain irradiation during childhood. However, the true incidence is not established, their biology is poorly understood, and few guidelines exist regarding the long-term follow-up of irradiated children. METHODS: We studied retrospectively patients irradiated for brain tumor under 18 years and followed in our institution since 1970. RIT were defined as new masses, different from the original tumor, occurring after delay in irradiated areas, and not related to phacomatosis. RESULTS: Among 552 irradiated patients, 42 (7.6%) developed one or more RIT, 26 months to 29 years after irradiation (mean 12.8 years). The cumulated incidence was 2.0% at 5 years and 8.9% at 10 years. Of the patients, 73.8% were adult at the time of diagnosis of RIT, and 75% were diagnosed within 18.1 years after irradiation. We identified 60 cavernomas, 26 meningiomas, 2 malignant gliomas, 1 meningosarcoma, and 6 thyroid tumors. Compared with meningiomas, cavernomas appeared earlier, in children irradiated at an older age, and with a male predominance. Although RIT were correlated with higher irradiation doses, 80.9% of these occurred at some distance from the maximum irradiation field. Twenty-five lesions were operated in 20 patients; three patients died because of progression of the RIT. CONCLUSION: A significant number of patients undergoing irradiation for brain tumor during childhood develop a RIT, often during adulthood. Our data suggest that radiation-induced cavernomas result from angiogenetic processes rather than true tumorigenesis. Protracted follow-up with MRI is warranted in children irradiated for brain tumor.

Role of radiosurgery in the management of cerebral arteriovenous malformations in the pediatric age group: data from a 100-patient series.

OBJECTIVE: To assess the safety and efficacy of radiosurgery for the management of arteriovenous malformations (AVMs) in the pediatric age group. METHODS: We reviewed data from 100 children (44 girls and 56 boys) presenting a total of 103 AVMs treated by linear accelerator radiosurgery between December 1988 and May 2002. The median patient age was 12 years (range, 2-16 yr). Sixty-seven AVMs (65%) were in functional locations and 30% were inoperable. The mean AVM volume was 2.8 cm3 (range, 0.9-21.3 cm3). The mean marginal dose was 23 Gy (range, 15-25 Gy) and required between one and four isocenters. Fifty patients received multimodal treatments with embolization and/or surgery before and/or after radiosurgery. Given that 16 patients underwent two sessions of radiosurgery and one patient received three sessions, a total of 119 radiosurgical treatments were delivered. We maintained our clinical and angiographic follow-up for at least 36 months after irradiation or until the complete obliteration of the AVM was confirmed by angiography (our sole end point for judging clinical efficacy). Univariate and multivariate analysis were performed to determine predictive factors for obliteration. RESULTS: Complete obliteration was achieved for 72 AVMs (70%). The permanent neurological deficit rate was 5%. One patient died because of rebleeding. None of our patients presented bleeding after an angiographically verified AVM obliteration. The main predictive factors for obliteration were low AVM volume and no previous embolization. Moreover, the younger the patient, the more effective the radiosurgery seemed to be. CONCLUSION: Radiosurgery is a safe and effective treatment for AVMs in the pediatric age group. One criterion for success was the use of a prescription dose similar to that used with adult populations.