Custom-designed plaque radiotherapy for nonresectable iris melanoma in 38 patients: tumor control and ocular complications

Abstract

Purpose: To evaluate plaque radiotherapy for iris melanoma.

Design: Prospective noncomparative interventional case series.

Methods: For 38 patients, custom-designed plaque radiotherapy using iodine 125 isotope was applied overlying the cornea with a tumor apex dose of 80 Gy. The main outcome measures were tumor control and ocular complications using Kaplan-Meier estimates and Cox proportional hazards regression analysis.

Results: In all cases, the melanoma was nonresectable owing to large or discohesive tumor. The tumor configuration was nodular in 24 cases (63%) and flat (diffuse) in 14 (37%). The mean tumor basal diameter was 9 mm (range 4 to 13 mm). Solid tumor extended into the anterior chamber angle in 36 eyes (95%). Tumor seeds were noted on the iris stroma for a mean of 7 clock hours and in the anterior chamber angle for a mean of 4 clock hours. Five-year follow up revealed tumor metastasis in 0% and tumor recurrence in 8% of patients. Visual acuity of 20/200 or worse was found in 16% at 5 years. Radiation-related complications at 5 years included corneal epitheliopathy (9%), cataract (70%), and neovascular glaucoma (8%). No patients developed corneal necrosis, scleral necrosis, retinopathy, or papillopathy. After treatment, the combined incidence of tumor-related and radiation-related elevated intraocular pressure at 5 years was 33%. Enucleation was necessary in 13% at 5 years, for tumor recurrence (n = 3) and patient preference (n = 1).

Conclusions: Plaque radiotherapy is a useful alternative to enucleation for eyes with nonresectable iris melanoma. Tumor control is 92% at 5 years, but related complications, especially cataract and elevated intraocular pressure, should be anticipated.