EPID-09. Characterizing the epidemiology of radiation-induced gliomas following cranial radiotherapy for pediatric cancers: a population-based study

Abstract BACKGROUND: Cranial radiotherapy (RT) is used to treat pediatric central nervous system (CNS) cancers and leukemias. RT carries a risk of secondary CNS malignancies, including radiation-induced gliomas, the epidemiology which poorly understood. METHODS: This retrospective study using SEER registry data (1975-2016) included two cohorts. Cohort 1 patients diagnosed with Grade III/IV or ungraded glioma as second malignancy >/=2 years after receiving beam radiation and/or chemotherapy for first at ages 0-19 years, either primary tumor treated (1a, n=77) leukemia unknown treatment (1b, n=20). 2 possible missed RIG who received then died presumed progressive disease more than 5 diagnosis, since previous studies have documented many RIGs in this group (n=296). Controls (n=10,687) all other did not fit inclusion criteria above. RESULTS: For (likely/definite RIGs), 0.97% cranial went on develop RIG. 3.39% tumors fell (possible RIGs). Median latency diagnosis was 11.1 years; significantly shorter 1b (median 10.0, range 5.0-16.1) vs. 1a (12.0, 3.6-34.4, p=0.018). OS 9.0 months. Receiving surgery, radiation, were associated non-statistically significant improvement (p 0.1-0.2). CONCLUSION: Within limitations population-based study, 1-4% undergoing later RIG, incurable can occur anywhere from 3-35 later. Effective remains unclear thus deserving increased attention preclinical clinical studies.