Regression Patterns of Iris Melanoma after Palladium-103 (103Pd) Plaque Brachytherapy.

PURPOSE To evaluate the patterns of regression of iris melanoma after treatment with palladium-103 (103Pd) plaque brachytherapy. DESIGN Retrospective, nonrandomized, interventional case series. PARTICIPANTS Fifty patients with primary malignant melanoma of the iris. METHODS Palladium-103 plaque brachytherapy. MAIN OUTCOME MEASURES Changes in tumor size, pigmentation, and vascularity; incidence of iris neovascularization; and radiation-related complications. RESULTS The mean age in the case series was 61.2±14.9 years. The mean tumor thickness was 1.4±0.6 mm. According to the American Joint Committee on Cancer, eighth edition, staging criteria for iris melanoma, 21 tumors (42%) were T1a, 5 tumors (10%) were T1b, and 24 tumors (48%) were T2a. The tumor was melanotic in 37 cases (74%) and amelanotic in 13 cases (26%); of these, 13 tumors (26%) showed variable pigmentation. After brachytherapy, mean tumor thickness decreased to 0.9±0.2 mm. Pigmentation increased in 32 tumors (64%), decreased in 11 tumors (22%), and was unchanged in 6 tumors (12%). For intrinsic vascularity (n = 19), 12 tumors (63%) showed decrease and 7 tumors (37%) showed complete resolution. Appearance of ectropion uveae showed diminution in 15 tumors (43%); newly present corectopia was observed in 6 patients (12%). On high-frequency ultrasound imaging, of the 42 tumors (84%) with low to moderate internal reflectivity, 30 tumors (60%) showed an increase in internal reflectivity on regression. Iris stromal atrophy was noted in 26 patients (52%), progression or new-onset cataract was noted in 22 patients (44%), neovascular glaucoma was noted in 1 patient (2%), and there were no cases of corneal opacity. There was no clinical evidence (0%) of radiation-induced retinopathy, maculopathy, or optic neuropathy. Mean follow-up in this series was 5.2 years (range, 0.5-17 years). CONCLUSIONS The most common findings related to iris melanoma regression after 103Pd plaque brachytherapy included decreased intrinsic tumor vascularity, increased tumor pigmentation, and decreased tumor thickness with synchronous increase in internal ultrasonographic reflectivity. No irreversible sight-limiting complications were noted.