Radiation-induced gliomas: report of 10 cases and review of the literature.

BACKGROUND: Radiotherapy and more recently radiosurgery represent important therapeutic methods for the treatment of tumors and arterovenous malformations affecting the central nervous system, even though several significant side-effects have been described (radionecrosis, tumors, etc.). Gliomas induced by radiation therapy are decidedly unusual, and the first descriptions of this association only appeared in the 1960s.

METHODS: The pertinent literature was reviewed to yield 116 cases in which a glioma developed after radiotherapy for cranial pathologies (included 10 personal cases treated in our Institution). One of our patients had undergone radiosurgery for a cavernous angioma.

RESULTS: Patients who developed a radiation-induced glioma were younger, as a group, than those affected with so-called "spontaneous" gliomas. The tumor originated in the previously irradiated area, after average doses of 32 Gy and an average latency period of 9.6 years in accordance with the findings reported by the authors and in our experience as well. Radiotherapy had most frequently been performed for acute lymphoblastic leukemia. Our Case 10 is the fourth case of intracranial tumor arising after radiosurgery to be described in the literature.

CONCLUSIONS: Though rare, gliomas may represent a late complication of radiation treatment. The behavior of the radiation-induced variety of glioma does not seem to differ significantly from that of its "spontaneous" counterpart. Late complications of the radiosurgery are probably underestimated because of the relatively recent introduction of this technique. On the contrary, these should be scrupulously evaluated when deciding whether to employ this method for therapeutic purposes for relatively benign or congenital lesions (which generally affect young patients with a long life expectancy).