HISTOPATHOLOGIC CHANGES FOLLOWING IRRADIATION FOR UVEAL TRACT MELANOMA

Histopathologic studies were performed on 38 eyes in patients with uve al melanoma who had enucleation. Of the 38 eyes examined, enucleation was required in 11 (29%) following episcleral radioactive plaque thera py (RPT), which was performed in 83 patients. The reasons for enucleat ion in the 11 patients who had RPT were progressive tumor in 5 and tre atment complications in 6 eyes. The histologic findings in these 11 pa tients were compared to those seen in 7 patients (18%) who received a planned course of preoperative external beam radiotherapy (RT) prior t o enucleation and with 20 uveal melanoma patients (53%) who were treat ed with enucleation alone. Tumor necrosis was found in the eyes of pat ients from all three groups examined. It was, however, seen more frequ ently and to a greater extent in the 11 RPT patients as compared to th e 7 preoperative RT and 20 enucleation alone patients, p = .01. There was no difference in the incidence or extent of tumor necrosis in the 7 preoperative RT patients as compared to the 20 primary enucleation p atients, p = .18. In all 3 study groups, no correlation was found betw een tumor size and necrosis. In the 11 RPT patients, necrosis was inde pendent of cell type and the radiation dose. As expected, the RPT pati ents had a greater incidence of neovascularization on the iris and scl eral necrosis than those of the other two study groups (70 vs. 12.5% a nd 33 vs 0%, respectively), p = .004. A major effort needs to be made to optimize episcleral RPT in order to reduce treatment complications and increase the incidence of primary tumor control.