Abstract
BACKGROUND: Factors associated with meningioma recurrence after postoperative radiotherapy are poorly understood, and the optimal postoperative radiotherapy target delineation for meningioma is unknown. The objective of this study was to identify factors influencing meningioma recurrence after postoperative radiotherapy to inform patient selection and treatment design. METHODS: Medical records were retrospectively reviewed for patients who underwent meningioma resection at a single institution between 1991 and 2015. Patients with sufficient tumor tissue for histologic classification and who received postoperative radiation therapy with external beam radiotherapy (EBRT), stereotactic radiosurgery (SRS) or brachytherapy, were included. Local freedom from recurrence (LFFR) was analyzed according to tumor and treatment characteristics using the Kaplan Meier method. RESULTS: We identified 86 patients with 96 meningiomas who met inclusion criteria. Nineteen meningiomas (20%) were WHO grade I, 56 (58%) were grade II and 21 (22%) were grade III. Forty-one meningiomas (43%) were recurrent, and 55 (57%) were de novo. The postoperative radiotherapy modality was EBRT for 58 patients (60%), SRS for 20 (21%) patients and brachytherapy for 18 (19%) patients. With a median follow up of 4.3 years (IQR 2.1–8.8 years), there were 48 (50%) local failures that occurred a median of 17 months after immediate prior resection (IQR 9–33 months). WHO grade II/III and recurrent meningiomas had worse LFFR (p< 0.001). The 5-year LFFR was 53% after EBRT (95% CI 41–69%), 53% after SRS (95% CI 34–84%) and 15% after brachytherapy (95% CI 3–74%), although meningiomas that were treated with brachytherapy were significantly more likely to have received prior EBRT or SRS (86% versus 29%, p< 0.001). CONCLUSIONS: These data provide a foundation for understanding patterns of meningioma recurrence after postoperative radiotherapy. Ongoing analyses aim to quantify the relationships between postoperative radiotherapy dose, target delineation and local control of meningioma.