Proton Beam Therapy for Iris Melanomas in 107 Patients

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

Retrospective study.

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

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.

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

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.

Proton therapy showed efficacy and limited morbidity in iris melanomas.