Impact of uveal melanoma thickness on post-plaque radiotherapy outcomes in the prophylactic anti-vascular endothelial growth factor era in 1131 patients

Abstract

Importance: The impact of tumour thickness on radiation complications following plaque radiotherapy for uveal melanoma in the anti-vascular endothelial growth factor (VEGF) era remains unknown.

Background: To evaluate treatment outcomes following plaque radiotherapy and prophylactic intravitreal bevacizumab for uveal melanoma based on initial tumour thickness.

Design: This was a retrospective, interventional case series.

Participants: Patients with uveal melanoma were included in this study.

Methods: A review of medical records was conducted of patients with uveal melanoma treated with plaque radiotherapy and prophylactic intravitreal bevacizumab from 7 July 2000 to 2 November 2018.

Main outcomes measures: Radiation-related outcomes of cystoid macular oedema (CME), radiation maculopathy, papillopathy, retinopathy, iris neovascularization (NVI) and neovascular glaucoma (NVG) were compared based on tumour thickness (small [<3.0 mm] vs medium [3.1-8.0 mm] vs large [>8.0 mm]).

Results: Of 1131 eyes, 341 (30%) had small, 633 (56%) medium and 157 (14%) large melanoma. Comparison (small vs medium vs large) at 4 years following radiotherapy revealed large melanoma with greater Kaplan-Meier estimated risk of CME (37% vs 37% vs 63%, P < .001), earlier onset of CME (33 vs 26 vs 19 months, P < .001) and greater development of NVI (<1% vs 2% vs 13%, P < .001) and NVG (1% vs 2% vs 12%, P < .001). Radiation-induced maculopathy, papillopathy and retinopathy were not associated with tumour thickness.

Conclusions and relevance: Compared with small and medium uveal melanoma, large uveal melanoma demonstrated greater 48-month risk for CME, shorter time to CME onset and greater development of NVI and NVG following plaque radiotherapy and prophylactic intravitreal bevacizumab.

Keywords: eye; melanoma; plaque radiotherapy; tumour thickness; uvea.