Retrospective analysis of ruthenium-106 brachytherapy for small and medium-sized malignant melanoma of the posterior choroid

Abstract

Transpupillary thermotherapy is a new and most promising treatment modality for up to medium-sized choroidal melanoma at the posterior pole. We analysed the results of conventional ruthenium-106 brachytherapy in these special tumour subgroup. Results of ruthenium-106 brachytherapy (radioactive dose to the tumour apex 150 Gy) in a series of 52 eyes with primary malignant choroidal melanoma (posterior to the equator, thickness </= 4.5 mm, base diameter </= 12 mm) were evaluated retrospectively. Mean tumour thickness was 3.2 mm. The posterior tumour margin was in 20 eyes </= 2 optic disc diameter away from the macula and in 10 eyes </= 2 optic disc diameter away from the optic disc. Follow-up was 3 - 9 years (median 5.6 years). Tumour control was achieved in 48 eyes (92 %): completely flattened scar in 71 %, residual prominence </= 2 mm in 16 %, no apparent response (but high reflectivity in ultrasonographic examination) in 5 %. 4 eyes were removed because of tumour regrowth (3 x) or secondary glaucoma (1 x). Visual outcome mainly depends on tumour location in respect of fovea and the optic nerve. Because 40 % of the eyes developed radiation maculopathy and 20 % radiation optic neuropathy 25 eyes (48 %) reached a final visual acuity </= 0.2. 40 eyes (77 %) revealed a visual loss of at least 2 lines. Two patients died of liver metastases. In posterior choroidal melanoma ruthenium-brachytherapy achieved an excellent rate of tumour control, but functional results were disappointing because of late radiation sideeffects. Transpupillary thermotherapy as an adjunct to ruthenium plaque radiotherapy may be able to reduce the radioactive dose.