(P019) Fractionated Robotic Stereotactic Radiosurgery for the Treatment of Benign Meningioma

Julia Vitti, Joyce Y. Chung, MD, Francis S. Cardinale, MD, Judith L. Gorelick, MD, Shane Lloyd, MD; Yale University School of Medicine; Connecticut Neuroscience

Purpose: Fractionated stereotactic radiosurgery (SRS) may offer several benefits in the treatment of symptomatic or growing meningioma but has not been examined extensively in the literature. Our primary aim was to describe the rates of tumor control and side effects in patients treated with CyberKnife SRS for meningioma.

Methods: We retrospectively reviewed 75 symptomatic or growing lesions treated in 72 consecutive patients who were unsuitable for or declined surgery (61 tumors, 83%) or had residual disease after resection (14 tumors, 17%) from 2008 to 2013. The study group included 31 skull base tumors, 27 falcine/parasagittal tumors, 7 tentorial tumors, 6 convexity tumors, 2 intraventricular tumors, and 2 spinal tumors. Patients were treated with a prescription dose of 25 Gy in five fractions. We calculated actuarial local control (LC) and progression free-survival (PFS) using the Kaplan-Meier method and recorded the rates of early adverse effects of treatment that may be related to peritumoral edema or proximity to cranial nerves or sinuses.

Results: The median follow-up was 21 months (range: 1–61 mo). Sixteen tumors (21%) were larger than 3 cm. The median conformity index was 1.5 (range: 1.2–2.2). At last follow-up, a decrease in tumor volume was seen in 5 tumors (7%), and 68 tumors (91%) were stable. Two-year LC was 98.6%. Overall, two tumors (3%) progressed, both in patients with grade 2 meningioma treated with SRS for progression after surgical resection. Two-year PFS was 97.2%. Early adverse effects were mostly temporary. Patients with parasagittal tumors experienced fatigue (14.8%), hair loss (11.1%), dizziness (11.1%), headache (3.7%), tinnitus (3.7%), facial pain (3.7%), near-syncope (3.7%), and temporary blurred vision (3.7%). Patients with nonparasagittal tumors experienced fatigue (26.7%), nausea (11.1%), headache (4.4%), and dizziness (2.2%). In three patients with optic nerve involvement, vision was unchanged at last follow-up.

Conclusions: CyberKnife radiosurgery resulted in a 97.2% 2-year PFS, but longer follow-up is needed to fully evaluate clinical efficacy. Patients who were poor candidates for surgery or single-fraction SRS were effectively treated with minimal adverse effects.