Objective: To assess treatment complications and tumor control after plaque radiotherapy for large posterior uveal melanomas measuring 8 mm or greater in thickness.
Design: Prospective noncomparative interventional case series.
Participants: Three hundred fifty-four patients each of whom had a posterior uveal melanoma measuring 8 mm or greater in thickness treated with plaque radiotherapy.
Main outcome measures: The four endpoints included (1) poor final visual acuity (20/200 or worse), (2) enucleation, (3) local tumor recurrence, and (4) metastasis. The clinical data regarding patient features, tumor features, and radiation parameters were analyzed for their impact on the four main outcomes using Cox proportional hazards regression models.
Results: Using Kaplan-Meier estimates, final visual acuity was poor in 57% at 5 years and 89% at 10 years follow-up. Using multivariate analysis, the most important risk factors for poor visual acuity included retinal invasion by melanoma, increasing patient age, iodine 125 (I(125)) isotope, and <2 mm distance to the optic disc. Treatment-related complications at 5 years included proliferative retinopathy (25%), maculopathy (24%), papillopathy (22%), cataract (66%), neovascular glaucoma (21%), vitreous hemorrhage (23%), and scleral necrosis (7%). Enucleation was necessary in 24% at 5 years and 34% at 10 years follow-up. Using multivariate analysis, the risk factors for enucleation included left eye, peripheral tumor margin anterior rather than posterior to the equator, increasing tumor thickness, and ruthenium 106 (Ru(106)) isotope. Using Kaplan-Meier estimates, local tumor recurrence was found in 9% at 5 years and 13% at 10 years follow-up. Using multivariate analysis, risk factors for tumor recurrence included Ru(106) radioisotope and ciliary body involvement with tumor. Tumor-related metastases were found in 30% at 5 years and 55% at 10 years follow-up. Using multivariate analysis, risk factors for metastases included inferotemporal meridian, anterior extension of the tumor to the iris root, increasing tumor base, and posterior margin < 2 mm from the optic nerve.
Conclusions: Plaque radiotherapy provided tumor control at 10 years in 87% of patients with selected large posterior uveal melanomas (>8 mm thick) that otherwise would have been managed with enucleation. The large intraocular mass and associated features and radiation complications led to poor visual acuity in most patients. At 10 years follow-up, enucleation was necessary in 34% of patients, and metastasis developed in 55% of patients.