NVTG-10 CLINICAL AND RADIOLOGICAL OUTCOMES OF ORBITAL METASTASES TREATED WITH STEREOTACTIC RADIOSURGERY: A SINGLE INSTITUTION RETROSPECTIVE SERIES

Abstract INTRODUCTION Orbital metastases (OM) are a rare complication of cancer that can result in visual impairment. Treatment options include surgery and radiotherapy, however, the optimal treatment for OM is unclear. The current evidence for stereotactic radiosurgery (SRS) is limited. We aim to report the efficacy and safety of SRS in patients with OM. METHODS The clinical and radiological outcomes of patients with OM treated with SRS between April 2006 and November 2023 were retrospectively reviewed. SRS was utilized to treat all the tumors. The post-treatment tumors were radiologically categorized to stable disease (SD), partial response (PS), and complete response per RECIST criteria. RESULTS We included 15 patients with 17 OM lesions in our study; 9 (60%) of whom were females, and their median age was 62 years (range: 21-82 years). The median overall survival was 6.5 months (range: 2-62 months). All these patients were treated with standalone CK SRS. The most common fractionation schedules were 24 Gy in 3 fractions (n=4). The median diameter of the lesions was 21 mm (range: 11-72 mm). The median volume treated was 2.6 cm3 (range: 0.3-78.8). At the last follow-up, 13 tumors (76.5%) showed SD, 2 tumors (11.8%) showed PR, 2 tumors (11.8%) showed CR, and no tumor (0%) showed PD. The lesions were followed for a median of 7 months (range: 2-62 months). The local control rates were 100% at 6-month and 12-month. No immediate or long-term radiation-induced necrosis was reported. CONCLUSION This is the largest series on OM treated with CK SRS with substantial follow-up data. Our study shows an excellent local tumor control with no immediate and long-term radiation induced necrosis.