Three-year outcomes of uveal melanoma treated with intra-operative ultrasound-guided iodine-125 brachytherapy using custom-built eye plaques

Purpose: The aim of this study was to demonstrate that uveal melanoma (UM) treated with eye plaque brachytherapy (EPB) with intra-operative ultrasound (IOUS) guidance results in increased local control. Material and methods: A retrospective study was conducted among 212 patients with 214 UM tumors treated by iodine-125 EPB with IOUS guidance from 2013 to 2019. 85 Gy was prescribed to tumor apical height or 5 mm from inner sclera, whichever was greater. Lesions were treated to 95% of 85 Gy at 2 mm margin from tumor edge. Local failure (LF), distant metastasis (DM), and radiation-related toxicity were recorded. Results: Median tumor apical height was 3.3 mm. COMS stage was 90 small (42.1%), 81 medium (37.9%), and 43 large (20.1%). Most patients had gene expression profile (GEP) class available, with 119 (55.6%), 30 (14.0%), 55 (25.7%) cases classified as 1A, 1B, and 2, respectively. Median dose at apex for tumor height > 5 mm and ≤ 5 mm was 85.0 Gy and 120.6 Gy, respectively. Outcomes data for 180 patients with over 12 months follow-up were reported. Mean follow-up was 37.3 months. Rates of LF and DM were 0.0% and 12.2%, respectively. Actuarial estimates of 5-year DM for class 1A, 1B, and 2 tumors were 2.5%, 0.0%, and 57.8%, respectively. 87 patients (48.3%) developed radiation-related toxicities. Conclusions: The excellent local control rate amongst lesions ranging across all sizes and GEP classes emphasizes the importance of image-guided brachytherapy with IOUS. We report favorable 5-year DM rates compared to established rates. Acceptable rate and severity of radiation-related toxicities were observed.