Plaque brachytherapy in iris and iridociliary melanoma: a systematic review of efficacy and complications

Introduction
To evaluate the efficacy and vision-threatening complication rate of plaque brachytherapy with iodine-125 (125I), palladium-103 (103Pd), and ruthenium-106 (106Ru) for treatment of iris and iridociliary melanoma.

Material and methods
A literature review was done based on results yielded from searching PubMed, Embase, and Cochrane database, using following key words: iris melanoma, iridociliary melanoma, brachytherapy, iodine-125 brachytherapy, palladium-103 brachytherapy, and ruthenium-106 brachytherapy. Initially, relationships between mean radiation dose to apex and local recurrence and complication rate were analyzed, and then, a comparison was performed between 125I, 103Pd, and 106Ru studies.

Results
Twelve retrospective and prospective studies were selected, with 491 patients treated primarily with plaque brachytherapy. The range of radiation dose to tumor apex were from 84 to 151.5 Gy. Ranges of mean and median of follow-up time were from 27 to 96 months. Local recurrence rate following brachytherapy ranged from 0 to 8%. A decrease in the average study dose was not associated with an increased local recurrence or metastasis rate (p = 0.373 and 0.195, respectively); however, an increase in radiation dose was associated with higher radiation-related cataract and glaucoma (p < 0.05). The rate of post-treatment glaucoma was higher in studies with 125I plaque brachytherapy (p = 0.004).

Conclusions
For brachytherapy of iris and iridociliary melanoma, in a range of 84 to 150 Gy, an increase in radiation dose may increase the risk of complications, while the tumor control rate does not change.