A Technical Report for Definitive Treatment of Uveal Melanoma With Stereotactic Radiosurgery and Retrobulbar Anesthesia

Abstract

Uveal melanoma (UM) is the most common primary intraocular malignancy, traditionally managed with episcleral plaque brachytherapy or enucleation. Single-fraction stereotactic radiosurgery (SRS) using a linear accelerator (LINAC) is an emerging alternative offering high precision and eye preservation. However, existing SRS/stereotactic radiation therapy (SRT) techniques often rely on mechanical immobilization or patient-maintained fixation. To the best of our knowledge, this is the first report of single-fraction, LINAC-based, frameless robotic SRS with retro- and peribulbar anesthesia for ocular immobilization from the United States. Additionally, we review the literature to assess local control, enucleation rates, and treatment-related toxicity of SRS/SRT for UM. Patients diagnosed with UM at our institution were evaluated by a multidisciplinary team of radiation oncologists and ophthalmologists. A thermoplastic mask and retro- and peribulbar anesthesia were used for ocular immobilization. Treatment planning involved computed tomography (CT) and magnetic resonance imaging (MRI) fusion for target delineation. Gross tumor volume (GTV) encompassed the entire tumor, with a 2 mm planning target volume (PTV) expansion and no clinical target volume (CTV). Treatment was delivered using the CyberKnife® system (Accuray Incorporated, Sunnyvale, California, United States) in a single 20 Gy fraction at the 80% isodose line, with real-time imaging for precise radiation delivery. Patients were monitored post-treatment for acute complications, with follow-up assessments of local tumor control, eye retention, and treatment-related toxicity. Additionally, we conducted a literature review of SRS/SRT studies, collecting data on patient numbers, tumor size, radiation regimens, immobilization techniques, and clinical outcomes, including local control, complications, and eye retention rates. This study demonstrates the feasibility of single-fraction, frameless LINAC-based SRS using CyberKnife with retro- and peribulbar anesthesia as an effective, patient-friendly alternative for treating UM. Patients with medium to large tumors are excellent candidates, even with a single 20 Gy fraction. This technique eliminates the need for mechanical eye immobilization while maintaining tumor control rates comparable to established modalities with potentially improved patient comfort. We aim to further evaluate our cohort's long-term patient outcomes, including local control, vision preservation, and late toxicities.