HISTOPATHOLOGY STUDIES IN MELANOMAS OF TH E CHOROID AFTER PROTON-BEAMIRRADIATION

To evaluate irradiation effects on choroidal melanomas, histopathologi c findings of 18 eyes whose primary treatment was enucleation were com pared to 15 eyes enucleated after proton beam irradiation. Irradiated tumors showed more likely necrosis (p = 0.01) had balloon cells (p = 0 .01), and inflammatory infiltrate (p = 0.05). lit the irradiated group , the prevalence of tumor blood vessel damage was higher (p = 0.0002) and mitotic figures were fewer (p = 0.01). These findings suggest that proton beam irradiation damages tumor. cells and alters the tumor's c apacity for cellular reproduction. It damages blood vessels leading to tumor necrosis. It induces an inflammatory response of unknown effect s. Radiosensitivity of choroidal melanomas cannot be assessed using co nventional histologic methods. However, tumor necrosis, mitotic activi ty and rare of balloon cells can help to establish tumoral sensitivity to irradiation.