Linear accelerator-based stereotactic fractionated photon radiotherapy as an eye-conserving treatment for uveal melanoma

Abstract

Background: The purpose of this retrospective analysis is to analyze clinical outcome, visual acuity and enucleation rates after linear accelerator-based stereotactic fractionated photon radiotherapy for primary uveal melanoma. Methods: Twenty-four patients with primary uveal melanoma treated at the Department of Radiation and Oncology of the University Hospital Heidelberg between 1991 and 2015 were analyzed regarding survival and treatment-related toxicity including eye- and sight-preservation. Results: Photon radiotherapy (RT) offered good overall local control rates with a local progression-free survival (LPFS) of 82% after 5years and a median LPFS of 5.5years at a median follow-up time of 5.2years. Gender had a significant impact on LPFS yielding a mean LPFS of 8.1years for women and 8.7years for men (p=0.04). Of all local progressions, 80% occurred within the first 5years after RT. In one case, enucleation as final therapy option was necessary. Enucleation-free survival (EFS) was related to the radiotherapy dose (p<0.0001). Thus, higher prescribed doses led to a significantly higher enucleation rate. T-stage had no significant impact on EFS, but affected the enucleation rate (p=0.01). The overall survival (OS) rate was 100% after 2years and 70% after 5years with a median OS of 5.75years. Age (p=0.046), T stage (p=0.019), local control rate (p=0.041) and the time between diagnosis and the first radiation session (p=0.01) had a significant effect on OS. Applied biologically effective dose (BED) did not significantly influence OS or PFS. A 2-year sight preservation rate of 75% could be achieved. In all patients, irradiation could be applied safely without any interruptions due to side effects. Six significant late toxicities with consequential blindness could be observed, making a secondary enucleation necessary in four patients. An impairment of visual acuity due to chronic optic nerve atrophy was identified in five patients within 2years after treatment. Conclusions: Linear accelerator-based stereotactic fractionated photon radiotherapy is an effective method in the treatment of uveal melanoma with excellent local control rates and a 2-year vision retention rate comparable to brachytherapy (BRT) or proton beam radiotherapy, even available in small centers and easy to implement. Interdisciplinary decision making is necessary to guarantee best treatment for every patient.