Clinical and radiological outcomes of orbital metastases treated with stereotactic radiosurgery: a single-institution retrospective series and review of the literature

OBJECTIVE Orbital metastases (OMs) 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. The aim of this study was to examine 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. Tumor response was categorized as stable disease (SD), partial response (PR), or complete response (CR) on follow-up imaging by RECIST (Response Evaluation Criteria in Solid Tumours) criteria. A review of the literature was also conducted in accordance with the PRISMA guidelines. RESULTS The authors included 15 patients with 17 OM lesions, 9 (60%) of whom were females. The median patient age was 62 years (range 21–82 years). The mean overall survival after treatment was 13.5 months (95% CI 2.34–24.66 months). All patients were treated with SRS using CyberKnife technology. The most common fractionation schedule was 24 Gy in 3 fractions (n = 4). The median lesion diameter was 21 mm (range 11–72 mm). The median volume treated was 2.89 cm 3 (range 0.12–56.11 cm 3 ). 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 progressive disease. The median follow-up was 24.5 months (range 0.5–126 months). The local control rates were 100% at 6 months and 12 months. No immediate or long-term radiation-induced side effects were reported. The literature review yielded 10 studies with 63 patients treated with SRS who had at least one follow-up imaging study. CONCLUSIONS This study presents the largest series of OMs treated with CyberKnife SRS in the literature. The authors observed an excellent local tumor control with no immediate or long-term radiation-induced necrosis, optic nerve injuries, or xerophthalmia.