Radiation retinopathy following plaque radiotherapy for posterior uveal melanoma.

Abstract

To identify the risk factors that lead to the development of radiation retinopathy following plaque radiotherapy for posterior uveal melanoma. Radiation retinopathy is a slowly progressive, occlusive vasculopathy characterized by radiation-induced endothelial damage. Review of the medical records of patients with posterior uveal melanoma treated with plaque radiotherapy. Of 1300 patients with posterior uveal melanoma treated with plaque radiotherapy from July 1, 1976, through June 30, 1992, radiation retinopathy developed in 560 (43.1%). By using Kaplan-Meier survival estimates, we found that 5% of the patients had nonproliferative radiation retinopathy at 1 year (95% confidence interval [CI], 3%-6%) and 42% at 5 years (95% CI, 38%-45%). The proportion of patients with proliferative retinopathy was 1% at 1 year (95% CI, 0.2%-1.5%) and 8% at 5 years (95% CI, 5%-10%). Multivariate analyses showed that the subset of clinical variables best related to the development of nonproliferative radiation retinopathy were tumor margin of less than 4 mm from foveola (P<.001), tumor limited to the choroid (P = .002), and radiation dose rate of greater than 260 cGy/h to the tumor base (P = .02). The best subset of independent variables related to the development of radiation maculopathy were tumor of less than 4 mm to foveola (P<.001) and the use of radioisotope iridium 192 (192Ir) (P = .02) compared with iodine 125 (125I). From a multivariate model, the most important factors for the development of proliferative radiation retinopathy included diabetes mellitus (P = .01), radioisotope 192Ir (P = .01) compared with 125I, and tumor base of greater than 10 mm (P = .02). Radiation retinopathy is a common finding after plaque radiotherapy for choroidal melanoma, occurring in 42% of patients at 5 years. The main predictors of radiation retinopathy are posterior tumor location with margin near the foveola and high radiation dose rate to the tumor base.