Radiation-induced tumors of the central nervous system occurring in childhood and adolescence. Four unusual lesions in three patients and a review of the literature.

The authors report four very rare radiation-associated tumors (or radiation-induced tumors; RITs) of the central nervous system (CNS) and review the literature on this topic. The purpose of this study was to determine the possible relationship between the harmful effects of radiation therapy, the shortest and the longest interval between the time of irradiation and the occurrence of the secondary tumor, and possible predisposing factors. The tumorigenic effects of therapeutic irradiation of the CNS have been mentioned in the literature, but the authors' literature search did not disclose either many reports of cases such as their own or a satisfactory and concise discussion on the different aspects of the late and catastrophic complications of this method of adjunct therapy to the CNS. Four rare cases of RIT in three patients are presented: a unique case of intradural meningioma of the cervical spine, which was irradiated successfully only for the patient to present with a new high-grade cerebral astrocytoma 4 years later, a paraventricular cavernoma and a fronto-temporo-orbital chondrosarcoma. These second RITs became symptomatic in the 17th, 16th and 15th years of life, respectively, in these young patients. The primary lesions were ependymomas, two in the IV ventricle and one in the left hemisphere. The time intervals between radiation and secondary tumor presentation were 14 and 18 years, 9 years and 28 months, in the order in which these patients presented. All the patients survived the second operation except the one with chondrosarcoma, who died in spite of repeated surgical interventions and adjunct therapies. It is concluded that the development of secondary RITs does not necessarily require a very long time interval; that although sarcomas are the most common RITs of the CNS in childhood and adolescence, benign and other rare and curable lesions may also occur in the field or vicinity of the field of radiation; and that in view of the possibility of occurrence of different types of RITs after varying time intervals in a single patient, whole-life followup of similar patients is mandatory.