Low dose iodine-125 brachytherapy and transpupillary thermal therapy for small- to medium-sized choroidal melanoma

COMS established iodine-125 (¹²⁵I) brachytherapy as standard of care for medium-sized choroidal melanomas. However, there remains a gap in the literature regarding reduced dosing for medium-sized choroidal melanomas and standard dosing for small-sized choroidal melanomas. We explored the impact of reduced dose ¹²⁵I brachytherapy on local tumor control and ocular adverse events (AEs).

Patients diagnosed 2005-2019 with choroidal melanoma <5 mm thick and managed with ¹²⁵I brachytherapy dose of 65 Gy to depth of 5 mm were included. Dose metrics were calculated using Monte Carlo-based dosimetry. Kaplan-Meier method was used to estimate overall survival and radiation-related AEs. Distant metastasis and local recurrence were reported using cumulative incidence with death as a competing risk. Univariate and multivariate associations were analyzed using Cox proportional hazards regression.

143 patients met inclusion criteria with median follow-up of 7 years. Five-year Kaplan-Meier estimates of ocular AEs were 59.6% radiation maculopathy, 42.0% cystoid macular edema, 55.2% nonproliferative radiation retinopathy, 10.8% proliferative radiation retinopathy, and 35.6% radiation papillopathy. Five-year cumulative incidence of local recurrence was 0%, 5-year cumulative incidence of distant metastasis was 6.1%, and 5-year Kaplan-Meier estimate of overall survival was 96.5%.

Reduced dose ¹²⁵I brachytherapy is feasible with excellent local tumor control.