Scleral necrosis after brachytherapy for uveal melanoma: Analysis of risk factors

Abstract

Radiation-induced scleral necrosis (RISN) is a rare, but a serious complication of brachytherapy for uveal melanoma. We aimed at analysing the incidence, timing and risk factors associated with development of RISN in a large institutional series. All consecutive cases with brachytherapy for uveal melanoma treated by the Departments of Ophthalmology and Radiotherapy at University Hospital Essen between 1999 and 2016 were eligible. Development of RISN during the post-treatment follow-up was recorded. A 1:2 propensity score matched case-control study was performed for the evaluation of the prognostic value of different tumour- and treatment-associated parameters. RISN was documented in 115 (2.9%) of 3960 patients with uveal melanoma included in the final analysis, and occurred at the mean 30.3months (range: 1.26-226 months) after brachytherapy. In the whole cohort, younger age (p= 0.042), plaque type (p= 0.001) and ciliary body involvement (p< 0.0001) were independently associated with the RISN occurrence. In the case-control study, multivariable weighted proportional hazard analysis discovered the association of the following additional tumour- and treatment-associated characteristics with RISN: posterior tumour margin anterior to equatorial region (p= 0.0003), extraocular tumour extension (p= <0.0001), scleral contact dose (p= <0.0001), conjunctival dehiscence after therapy (p= 0.0001), disinsertion of the superior rectus muscle (p= 0.001) and the glaucoma medication (p= 0.014). Our study confirms RISN as a rare complication, which might occur even years later after the brachytherapy for uveal melanoma. Alongside with scleral dose five other tumour and therapy related factors predict the risk of RISN after brachytherapy for uveal melanoma were established.