Objective: This study aimed to determine whether the long-term melanoma-specific mortality rate of patients with a primary choroidal or ciliary body melanoma treated by enucleation is appreciably lower than that of similar patients treated by plaque radiation therapy.
Design: Retrospective, nonrandomized, comparative clinical trial.
Participants: A previously reported group of 237 patients, 140 treated by enucleation and 97 treated by cobalt-60 (Co-60) plaque between May 1976 and June 1980, and a residual group of 122 patients, 51 treated by enucleation and 71 treated by Co-60 plaque, were identified by variable-by-variable range matching.
Intervention: Primary treatment by enucleation or Co-60 plaque radiation therapy was performed.
Main outcome measures: Melanoma-specific mortality and duration of post-treatment survival were measured.
Results: The melanoma-specific mortality rate was substantially worse in the original enucleation subgroup over the entire 15-year follow-up interval; however, differences in baseline prognostic factors between the subgroups are likely to explain the difference in survival curves. After elimination of patients with nonoverlapping values of individual clinical variables to adjust for recognized intergroup differences at baseline, there was no significant or clinically important difference in the 15-year mortality curves of the residual subgroups. The relative rate ratio for the treatment effect in the residual patients was 0.97 (95% confidence interval, 0.51-1.86). There was no late downturn in the survival curve of the plaque-treated patients or late crossing of the curves.
Conclusion: A large difference in survival between equivalent groups of patients with primary choroidal or ciliary body melanoma treated by enucleation versus plaque radiation therapy appears to be unlikely.