Stereotactic radiosurgery and radiotherapy for meningiomas: biomarker predictors of patient outcome and response to therapy.

Although surgery has traditionally been the primary treatment of meningiomas, stereotactic radiosurgery (SRS) and radiotherapy (SRT) techniques have become a standard part of the treatment approach to intracranial meningiomas. For incompletely resected or inoperable benign meningiomas, SRT and SRS can provide excellent 5-year tumor control rates in 90% to 95% of benign meningioma cases. The current data on prognostic factors in meningioma SRT and SRS treatment outcomes are sparse. Our study aims to define prognostic factors that may help determine meningioma SRT and SRS treatment outcomes. Outcomes of 162 patients with 166 intracranial meningiomas treated with SRT (80 treatments) or SRS (92 treatments) were examined. Patient characteristics and tumor hypoxia-regulated biomarkers were correlated with tumor local control and overall survival. Median follow-up was 52 months, with median tumor volumes and treatment doses of 2.72 cm/15 Gy and 12.54 cm/54 Gy for SRS- and SRT-treated patients, respectively. Local control occurred in 68/77 (88.3%) SRT-treated patients and 80/89 (89.9%) SRS-treated patients. Tumor volume was predictive of overall survival for patients treated with SRT. The hypoxia-related biomarkers VEGF, HIF-1, and MIB-1 were useful in predicting outcome after SRT and SRS. SRS and SRT are successful in controlling intracranial meningioma growth. With further study, HIF-1, VEGF, and MIB-1 may be useful as predictive markers for response to SRT and SRS.