RONC-18. ANALYSIS OF BRAIN TUMOR INDUCED BY IRRADIATION IN CHILDHOOD - A SINGLE INSTITUTIONAL ANALYSIS

BACKGROUND: Radiation-induced brain tumors are rare tumors that appear during long-term follow-up after radiation therapy. Children are at greater risk for radiation -induced brain tumors than adults. The clinical characteristics of radiation-induced brain tumor treated at our hospital were retrospectively examined. PATIENTS AND METHODS: Clinical characteristics of seven radiation-induced brain tumors that developed in 6 patients irradiated in their childhood at our hospital were analyzed. The background disease, age at irradiation, irradiation dose, period from irradiation to onset, pathological diagnosis, and treatment for radiation-induced brain tumor were examined. RESULTS: Background diseases for irradiation were leukemia in 3 patients, germinoma in 2, medulloblastoma in 1, and the average cranial irradiation dose was 23.2 Gy. The patients tended to be young at irradiation (2–17 yeays; median:4 years old). The time between irradiation and the onset of radiation-induced brain tumors ranged from 9.5 to 39.1 years (median:28 years). Radiation-induced brain tumors comprised 6 meningioma（grade I:5, grade II:1）and 1 high-grade gliomas. All patients underwent surgical removal of the radiation-induced brain tumors and 2 received additional irradiation. During a median of 5.3 years of follow-up after the diagnosis of radiation-induced brain tumors, 2 underwent second surgery, while the remaining 4 have no recurrence. DISCUSSION: In most cases, radiation-induced brain tumors occur for a long time after irradiation in childhood. Monitoring of radiation-induced brain tumors as well as primary tumor recurrence was considered important.