Characterization and incidence of radiation-induced meningiomas in a brain tumor database

Purpose: Radiation-induced meningiomas (RIMs) are meningiomas that associated with prior exposure to radiation. Due to the rare occurrence of RIMs, their behavior has not been well described and their incidence has not been reported. This study aims to characterize RIMs and compare the treatment and outcomes of RIMs to those of spontaneous meningiomas (SMs). Methods 1003 patients seen at a single institution with proven or presumed meningiomas were identified from brain tumor-related diagnoses between 2005 and 2015. Chart review positively-identified patients with RIMs and data was collected on initial diagnosis and treatment, meningioma recurrence/progression, histology, and treatments. Results Fifteen RIM patients were identified (66.67% were female and 66.67% were Caucasian). The average age at diagnosis was 43.27 ± 15.06 years. The overall mean latency was 356.27 ± 116.96 months. The mean latency period for the African-American population was 258.4 ± 84.86 months compared to 405.2 ± 100.5 months for the Caucasian population (p = 0.003). The mean number of lesions for males was 1.4 ± 0.89 compared to females which was 2.8 ± 1.40 (p = 0.046). The incidence of RIMs among all meningiomas in our data set was 1.5%, a statistic that has not previously been reported. The 10-year progression-free survival rate and recurrence-free survival rate was 50% and 27%, respectively. 58% of patients treated with radiotherapy were progression-free at 5 and 10 years. Conclusion Radiation remains a rare but important cause of meningioma. These meningiomas have a higher grade histology, require aggressive treatment strategies, and have higher recurrence and progression compared to spontaneous meningiomas.