EPISCLERAL PLAQUE THERMORADIOTHERAPY OF POSTERIOR UVEAL MELANOMAS

Episcleral plaque radiotherapy is a widely applied treatment for selec ted patients with uveal melanomas. This treatment is well tolerated bu t may produce severe late radiation complications resulting in decreas ed visual acuity that reduces the attractiveness of conservative thera py. The purpose of this study was to assess if the addition of episcle ral hyperthermia decreases late radiation complications through radiat ion dose reduction while maintaining high incidence of local tumor con trol. In a 3-year period, episcleral plaque thermoradiotherapy was giv en to 25 patients with uveal melanoma in a Phase I study. The mean tum or height was 6.2 mm and the mean tumor basal area was 173 mm(2). The mean radiation dose given to the tumor apex was 72.2 Gy and the mean h yperthermia temperature, given once for 45 min, was 43.5 degrees C. Of the 25 patients treated, 22 (88%) showed tumor height reduction, 2 (8 %) showed no change, and 1 (4%) had an increase in tumor height. At th e last follow-up (range, 20-68 months; mean, 31.2 months), a 43% mean tumor height reduction was recorded (p = 0.0002). Of the 22 patients i nitially showing tumor regression, 2 (9%) had subsequent tumor progres sion. At least ambulatory vision (>5/200) was maintained by 20 (80%) p atients. Severe complications, including hemorrhagic retinal detachmen t and a large vitreous hemorrhage, were seen in 2 (8%) patients early in this Phase I study. The treatment program was well tolerated by the study patients. Severe late treatment toxicity was sharply reduced by limiting the mean scleral temperature to less than or equal to 44 deg rees C. This study employing 30% lower radiation doses, showed tumor r egression in the majority of patients. Longer follow-up is needed to a ssess long-term treatment efficacy and late treatment complications.