• Rajni A Sethi, Stephen C Rush, Shian Liu, Suresh A Sethi, Erik Parker, Bernadine Donahue, Ashwatha Narayana, Joshua Silverman, Douglas Kondziolka, and John G Golfinos.
• *Department of Radiation Oncology, University of California San Francisco, San Francisco, CA Departments of †Radiation Oncology ‡Neurosurgery, New York University School of Medicine, New York ∥Department of Radiation Oncology, Maimonides Medical Center, Brooklyn, NY §Department of Environmental Science, Alaska Pacific University, Anchorage, AK.
• Am. J. Clin. Oncol. 2015 Dec 1; 38 (6): 600-4.

ObjectiveDose-response relationships for meningioma radiosurgery are poorly characterized. We evaluated determinants of local recurrence for meningiomas treated with Gamma Knife radiosurgery (GKRS), to guide future treatment approaches to optimize tumor control.Materials And MethodsA total of 101 consecutive patients (108 tumors) who underwent GKRS for benign, atypical, or malignant meningiomas between 1998 and 2011 were studied. Local recurrence was assessed. Cox proportional hazards and logistic regression analyses were used to determine the association of patient-related, tumor-related, and treatment-related characteristics with local recurrence. Acute and late toxicity was evaluated.ResultsWorld Health Organization (2007 classification) tumor grade was I (82%), II (11%), or III (7%). Median dose was 14 Gy (range, 10 to 18 Gy) for grade I tumors and 16 Gy (range, 12 to 20 Gy) for grade II and III tumors. Median follow-up was 25 months (maximum, 17 y). Two- /5-year actuarial local control rates were 100%/98% for grade I tumors and 76%/56% for grade II/III tumors. Higher tumor grade and lower GKRS dose were associated with local failure. In this cohort, there was a 42% relative reduction in local recurrence for each 1 Gy of dose escalation.ConclusionsTreatment was well tolerated with no moderate or severe toxicity. Tumor control was excellent in benign tumors and suboptimal in higher grade tumors. Because the main determinant of local recurrence was GKRS dose, we recommend dose escalation for atypical or malignant tumors to doses between 16 and 20 Gy where critical structures allow.

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