Proton Beam Therapy for Iris Melanomas in 107 Patients.

Purpose: To report on the clinical characteristics and outcomes for patients with iris melanoma using proton therapy.

Design: Retrospective study.

Participants: One hundred seven patients with iris melanoma from 3 regional ophthalmologic centers.

Methods: A retrospective study was conducted for iris melanoma patients from 3 regional ophthalmologic centers referred to and treated at a single proton therapy facility between 1996 and 2015.

Main Outcome Measures: At each follow-up visit, examinations included measurement of best-corrected VA, slit-lamp, examination, indirect ophthalmoscopy, and ultrasound biomicroscopy.

Results: With a median follow-up of 49.5 months, 5 of 107 patients experienced a local relapse within a median of 36.3 months. The cumulative incidence of relapse was 7.5% at 5 years. All 5 patients showed involvement of the iridocorneal angle (P = 0.056). Diffuse iris melanoma showed a higher risk of relapse (P = 0.044). Four patients showed out-of-field relapse and 1 showed angular relapse. Three patients were retreated with proton therapy, whereas 2 other patients, one with T1b disease and another with diffuse T3 disease, underwent secondary enucleation. None of the patients experienced metastases nor died of iris melanoma. Vision improved in 59.4% of patients (n = 60/101). However, cataracts occurred in 57.4% of the 54 patients (n = 31) without cataract or implant at diagnosis. Secondary glaucoma was reported in 7.6% of the patients (n = 8), uveitis in 4.7% (n = 5), and hyphema in 3.7% (n = 4). All but 5 cases of complications were mild, transient, and not sight limiting after treatment. Five cases of glaucoma, including 1 with uveitis, were severe and associated with visual deterioration.

Conclusions: Proton therapy showed efficacy and limited morbidity in iris melanomas.