Outcomes of I-125 brachytherapy for uveal melanomas depending on irradiation dose applied to the tumor apex – a single institution study

Purpose
The aim of the study was an evaluation of I-125 brachytherapy patients with uveal melanoma with special consideration for the relationship of the treatment results and the irradiation dose applied to the tumor apex.

Material and methods
Medical records of 344 adults with uveal melanoma treated with I-125 brachytherapy in the Department of Ophthalmology and Ocular Oncology of the Jagiellonian University, Medical College in Cracow, Poland were retrospectively analyzed. The study was conducted between 2003 and 2012, and the study group was divided into two subgroups depending on the irradiation dose applied to the top of the tumor: 80 Gy to 100 Gy (n = 177) and 100 Gy to 120 Gy (n = 167).

Results
It was found that the height of the tumor and the largest diameter of the tumor base decreased with every consecutive follow-up measurement and differed significantly in all comparisons (p < 0.0001). No significant correlation between frequency of complications was found between both study groups (χ2 = 0.27; p = 0.6067). The correlation between survival and the irradiation dose as applied to the tumor top was statistically irrelevant (χ2 = 0.44; p = 0.5084). A logistic regression model showed that patient survival depended on the largest diameter of the base and the height of tumor (p = 0.0216), and the risk of death was larger as these dimensions increased (IR, 1.17). An increase of the largest diameter of the base by 1 mm meant a 17% increase in chances of death. In 13.4% of cases, an enucleation was necessary.

Conclusions
The treatment of choroidal melanomas with I-125 iodine isotope brachytherapy is an efficient and recommended method of treatment and in many cases, an alternative to the enucleation of an eyeball.