Dose de-escalation with gamma knife radiosurgery in the treatment of choroidal melanoma.

Abstract

Single-fraction targeted radiation therapy delivered by the Leksell Gamma Knife system is a minimally invasive treatment option for choroidal melanoma that has been used as an alternative to enucleation, proton beam therapy, or brachytherapy. Previously reported Gamma Knife series involved the treatment of choroidal melanomas with a dose of 40 to 50 Gy at the tumor margin. We report our institutional experience using a significantly lower dose. Fourteen patients with choroidal melanoma were treated with the Leksell Gamma Knife at our institution over a 7-year period. The treatment and clinical data were analyzed in a retrospective fashion after a mean follow-up of 32.2 months. The mean dose to the tumor margin was 22.2 +/- 2.4 Gy (range, 20- 25 Gy). Mean treated tumor volume was 1.1 +/- 1.2 cc. Local control was achieved in 13 cases (93%). In 1 patient both intraocular spread and distant metastatic disease developed after treatment. Visual function of the affected eye was preserved in 5 patients (36%) at latest follow-up, in 9 patients (64%) visual loss ensued. Mild to moderate radiation toxicity developed in 8 patients. Choroidal melanoma can be safely and effectively treated using Leksell Gamma Knife stereotactic radiosurgery with a marginal dose of less than 25 Gy.