Iodine-125 irradiation of choroidal melanoma. Clinical experience.

Twenty-nine patients with choroidal melanomas were treated with iodine-125 seeds in gold scleral plaques. Iodine-125 emits low energy 25 KeV photons which are attenuated by the side and back of the plaques so that the radiation is "directed" towards the choroidal tumor. The anticipated therapeutic benefits of using a low energy isotope and directional applicators have been realized. There has been a marked reduction in ocular complications in the nine medium and 20 large melanomas so treated. Our complication rate was 34% with a mean follow-up of 38 months. This is a lower complication rate, with longer follow-up, and in larger tumors than that reported with the use of cobalt-60, ruthenium-106 or ion beam. Three patients with large tumors and two patients with medium tumors died of metastasis. This compares favorably to results of similarly sized melanomas treated by enucleation.