Post-irradiation regression of choroidal melanomas as a risk factor for death from metastatic disease.

To determine the prognostic value of the regression rate of choroidal melanomas after cobalt-60 plaque radiotherapy, the authors performed a multivariate analysis on 159 patients treated with a cobalt plaque during the interval from 1976 through 1980. Thirty-three of the 159 patients had died as of the survey date; 29 of metastatic melanoma and 4 of other causes. Multivariate Cox proportional hazards modeling identified a two-term regression incorporating maximal basal tumor diameter at treatment and tumor thickness at 12 months posttreatment as the best model (P less than 0.005 for both parameters) for predicting length of tumor-free survival. These results are consistent with the hypothesis that rapid regression of a choroidal melanoma after cobalt-60 plaque radiotherapy is an unfavorable prognostic sign for prolonged metastasis-free survival.