Proton irradiation for peripapillary and parapapillary melanomas

To examine ocular outcomes and survival after proton irradiation in patients with peripapillary and parapapillary melanomas ineligible for the Collaborative Ocular Melanoma Study.

A total of 573 patients who received proton irradiation from January 4, 1985, through December 24, 1997, for tumors located within 1 disc diameter of the optic nerve, and therefore ineligible for the Collaborative Ocular Melanoma Study, were evaluated. Cumulative rates of vision loss in the treated eye, eye loss, melanoma-related mortality, and tumor recurrence were estimated using the Kaplan-Meier method.

Most (53.4%) tumors abutted the optic disc; median distance from the tumor to the macula was 0.5 disc diameters. By 5 years after proton therapy, radiation papillopathy had developed in 56.8% and maculopathy in 60.4% of patients. Of 450 patients with a baseline visual acuity of 20/200 or better in the treated eye, vision was retained in 54.9% at 2 years after irradiation. This decreased to 20.3% by 5 years after treatment, although 56.2% had visual acuity of counting fingers or better. Five- and 10-year rates of local recurrence were 3.3% and 6.0%, respectively. Enucleation rates were 13.3% at 5 years and 17.1% at 10 years after treatment. Melanoma-related mortality rates were similar to those in our larger cohort of patients (24.0% at 15 years).

Proton irradiation should be considered for treating patients with tumors contiguous to the optic disc. Although visual acuity is compromised, some preservation is possible (counting fingers or better in many patients). Eye conservation is likely, with low rates of tumor recurrence and no increased risk of metastasis.