Stereotactic Radiosurgery Outcomes for Radiation-Induced Meningiomas After Childhood Tinea Capitis Irradiation: A Comparative Study with Sporadic Meningiomas.

BACKGROUND: Childhood scalp irradiation for tinea capitis (TC) increases the long-term risk of intracranial meningiomas. It remains unclear whether prior TC irradiation affects meningiomas' response to stereotactic radiosurgery (SRS). We compared TC-irradiated and sporadic meningiomas treated with SRS. METHODS: Among 539 meningioma patients treated with SRS from 2010-2023, 204 met criteria for volumetric analysis (median follow-up 64.6 months, IQR 32.8-107.8). Of these, 61 (29.9%) had childhood scalp irradiation for TC, while 143 (70.1%) had no prior cranial irradiation. Tumor volumes were measured on T1-weighted gadolinium-enhanced MRI baseline and at last follow-up, or prior to surgery. Treatment response was assessed as percent volume change, as a binary study-defined "good response" (≥29% reduction), and RANO-aligned categories. Predictors of response and surgical intervention were evaluated using multivariable regression. RESULTS: TC-irradiated patients were older (median 67.6 vs. 62.8 years, P < .001) and more commonly had multiple meningiomas (73.8% vs. 11.9%, P < .001) than non-irradiated patients. Baseline tumor volume was similar between groups (P = .516), as was the need for surgical resection (P = .535). Multivariable analysis showed that TC irradiation independently predicted poorer volumetric response (a + 38.7% relative volume change, P = .026) and a lower likelihood of achieving the study-defined "good response," although this was not statistically significant. TC irradiation was not associated with progression-free survival. CONCLUSIONS: Childhood TC irradiation-related meningiomas are a distinct subgroup characterized by multifocality and reduced volumetric response to SRS. These findings suggest a potentially treatment-resistant phenotype, supporting the need for individualized management.