Purpose: To estimate the risk factors responsible for unsuccessful treatment of melanoma with episcleral plaque brachytherapy.
Material and methods: Based on 23 cases of choroidal melanoma, in which the eyes had to be enucleated after earlier brachytherapy, clinical characteristics of the tumors, type of plaque therapy and reasons of enucleation were analysed. Histopathologic examination of enucleated eyes was performed by standard techniques and immunohistochemical stains on formalin-fixed paraffinembedded tumor tissues.
Results: Tumor size is the most valuable risk factor for prognosis in plaque brachytherapy of melanoma. The direct indications for enucleation were: increase of tumor mass, optic disc invasion, consecutive glaucoma and extrascleral extension. Histopathological examination revealed 17 mixed-cell melanoma, 4 spindle-cell, 1 epithelioid and 1 necrotic. Post-irradiation necrosis was found in only 6 tumors.
Conclusions: It is very difficult to predict the results of conservative treatment of melanomas basing on their clinical characteristics. The aggressive nature of the tumors and their resistance to irradiation seem to be the likely explanation of failures.