Late radiation failures after iodine 125 brachytherapy for uveal melanoma compared with charged-particle (proton or helium ion) therapy

Abstract

Objective: To evaluate late (more than 5 years) radiation failures after uveal melanoma treatment.

Design: Comparison of three retrospective, interventional, partially randomized case series.

Participants: Nine hundred ninety-six patients who were treated in several phase I, II, and III trials of uveal melanoma radiation.

Main outcome measures: Follow-up period, treatment history, recurrence rates, type of recurrence, and mortality associated with late local recurrences.

Results: Eleven of 996 irradiated uveal melanoma patients experienced intraocular recurrence more than 5 years after radiation. All 11 of these patients were treated with iodine 125 ((125)I) brachytherapy. Late recurrences were detected between 5.5 to 15.3 years after treatment. These patients did not have either high-risk clinical parameters (thin, posterior tumors in proximity to the optic nerve) or radiation dosimetry characteristics (low dose-delivery radiation) associated with a known increased risk for tumor recurrence after radioactive plaques. The annualized incidence rate for regrowth was 1.9% per year between 5 and 15 years after (125)I brachytherapy. In contrast to charged particles, the risk of late recurrence after (125)I brachytherapy continued with increased follow-up.

Conclusions: There was a significantly higher late recurrence rate with (125)I brachytherapy as compared with charged particle radiation. Although tumor enlargement 5 or more years after radiation can be the result of intratumor hemorrhage, in a patient treated with radioactive plaque, a late failure is a distinct possibility.