RTHP-13. EFFICACY OF FRACTIONATED GAMMA KNIFE RADIOSURGERY FOR ORBITAL CAVERNOUS HEMANGIOMA: 10-YEAR EXPERIENCE AT A SINGLE INSTITUTION

Abstract

Abstract This study aimed to evaluate the efficacy and safety of fractionated gamma knife radiosurgery (GKS) for the treatment of orbital cavernous hemangioma (OCH). METHODS From January 2007 to June 2018, 34 patients who underwent fractionated GKS (median 20 Gy in 4 fractions) for OCH at a single tertiary institution were reviewed. Ophthalmic evaluations including exophthalmometry, best corrected visual acuity with the Snellen chart and Humphrey visual field were investigated. Changes in lesion volume were also analyzed. RESULTS The median age was 43 years (range, 10–67 years) and 18 patients were male (53%). The median clinical follow-up time was 42 months (range, 12–132 months). The most common presenting symptom was proptosis followed by visual impairment. Proptosis improved in all 27 patients. The mean value of proptosis was reduced from 2.9 mm to 1.1 mm (P < 0.001). Of 15 patients who showed decreased visual acuity preoperatively, 12 patients (80%) had improved in vision. Preoperative visual field defects were evident in 17 patients and resolved in 15 patients (88%) after treatment. The median tumor volume at the time of GKS was 2.2 cm3 (range, 0.2–8.5 cm3). Tumor shrinkage was observed in all patients and the mean volume reduction rate was 64%. No patient experienced GKS-related ocular morbidity, though two transient GKS-related adverse events (6%) were observed. CONCLUSION Fractionated GKS is an effective and safe option for the treatment of OCH, with significant reduction in tumor volume and improvement of ophthalmic outcomes.