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A. Russo, B. Damato; An Audit of Eccentrically-Positioned Ruthenium Plaque Radiotherapy of Choroidal Melanoma in Liverpool. Invest. Ophthalmol. Vis. Sci. 2009;50(13):5770.
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Brachytherapy is usually administered with the plaque overlapping the entire tumor margin by at least 1-2mm. With posterior tumors, our practice is to position the plaque with its posterior edge aligned with the posterior tumor margin. We audited ocular outcomes after eccentrically-placed ruthenium plaque radiotherapy of choroidal melanoma.
Patients were included if receiving primary ruthenium brachytherapy for choroidal melanoma during the three years up to the 31st July 2007. A perforated template was used to facilitate plaque positioning. For posterior tumors, the template was positioned so that transillumination produced a glow at the posterior tumour margin (‘sunset sign’). Minimum doses of 300-350 Gy and 80-90 Gy were prescribed to the sclera and apex respectively.
The cohort comprised 162 patients (93 female and 69 male). The time to the last known visual acuity had a median of 23 months. The initial visual acuity was 20/40 or better in 94.6%, 20/60 to 20/200 in 13.0% and worse than 20/200 in 1.9% of patients. The tumors had a mean basal diameter of 11.7mm. Ten tumors exceeded 5.4 mm in height. Tumor extension to within 5mm of optic disc, fovea or both occurred in 18 (11.1%), 28 (17.3%) and 27 (16.7%) cases respectively. Risk factors for visual loss were proximity to optic disc or fovea, initial visual acuity worse than 20/40 and tumor height exceeding 5.4 mm. In 66 patients with none of these risk factors, 92% retained 20/40 or better and 5 had vision of 20/60 - 20/200. In 72 with one risk factor, 74.3% retained 20/16 - 20/40 and 95.7% had vision of 20/200 or better. In 12 patients with 2 risk factors, these percentages were 25.0% and 91.7%. Only 3 patients had 3 risk factors and one retained vision of 20/200 or better. Three patients had local tumor recurrence and were treated respectively by proton beam radiotherapy, plaque radiotherapy and enucleation (the only eye lost in this series).
Eccentric plaque radiotherapy of choroidal melanoma achieves good rates of local tumor control, ocular retention and preservation of vision.
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