High-dose radiation-induced meningiomas. Report of five cases and critical review of the literature.

Radiotherapy is an important modality for the treatment of tumors and arteriovenous malformations affecting the central nervous system, even though several significant side effects have been described (radionecrosis, tumors, etc.). Meningiomas induced by high-dose radiation therapy are uncommon. In this study we describe five cases treated at our institute and review all previously published reports of meningioma occurring after high-dose radiotherapy. These tumors develop mainly in patients irradiated in childhood; their incidence peaks in the second decade of life, there is a predominance in females and a high frequency of malignant forms. Although rare, meningiomas may represent a late complication of radiation treatment. The behavior of the radiation-induced variety of meningioma seems to differ from that of its "spontaneous" counterpart. The use of radiotherapy should be carefully evaluated for relatively benign or congenital lesions which generally affect young patients with a long life expectancy.