Eccentric ruthenium plaque radiotherapy of posterior choroidal melanoma

Background The aim of this work is to report on conservation of visual acuity after eccentric ruthenium 106 (Ru-106) brachytherapy of posterior choroidal melanoma. Methods Fifty-four patients with choroidal melanoma extending to within 5 mm of the optic disc or fovea were treated at a single institution during the 3 years up to July 31, 2007. The plaque was positioned eccentrically with its posterior edge aligned with the posterior tumor margin to reduce the radiation dose to the optic disc and fovea. The main outcome measures were local tumor control and conservation of vision of 6/12 or better, according to baseline variables. Results The tumors had a mean longest basal diameter of 12.0 mm and a mean thickness of 3.1 mm. The posterior tumor margin extended to within 3 mm of the fovea in 30 patients (56%). In the 24 eyes with the posterior tumor margin located 3.1–5.0 mm from the fovea, 74.9% retained visual acuity of 6/12 or better 4 years after treatment (95% confidence interval [CI], 55.5–94.3%). In the 30 eyes with tumor extension to within 3.0 mm of the fovea, then 3 years after treatment only 25.3% retained such vision (95% CI, 5.3–45.3%). Recurrence at the posterior tumor margin occurred in two patients. Conclusions Eccentric ruthenium 106 plaque radiotherapy of posterior choroidal melanoma achieves good rates of local tumor control and conservation of vision if special measures are taken to ensure that the plaque is positioned correctly.