Regression of posterior uveal malignant melanomas after cobalt plaque radiotherapy.

We reviewed the records of 17 patients with posterior uveal malignant melanoma who had been followed for at least 3 months prior to cobalt plaque radiotherapy and whose tumor had been documented to enlarge in thickness during that interval. We evaluated the relationship between the rates of pretreatment tumor enlargement and post-treatment tumor shrinkage using linear regression analysis. We found that the rate of postirradiation tumor shrinkage correlated strongly with the rate of preirradiation tumor enlargement regardless of whether the pretreatment rate of growth was slow, intermediate or rapid. We speculate that the more rapidly regressing tumors were more mitotically active than their more slowly regressing counterparts. If true, the survival rate of patients whose posterior uveal malignant melanomas regress rapidly following radiation therapy may prove to be worse than that of patients whose tumors regress slowly.