Clinical characteristics and postoperative complications as predictors of radiation toxicity after treatment with I125 Eye Plaque Brachytherapy for Uveal Melanomas

Purpose/Objective(s) I125 Eye Plaque brachytherapy is the standard treatment for medium size uveal melanomas. As a result, most patients have late radiation toxicities (RTT) such as radiation-induced maculopathy (RM), radiation-induced neovascular glaucoma/iris neovascularization (RNGI) and radiation-induced optic neuropathy (RON) that result in vision loss. While tumor size, location and radiation dose have been identified as predictors of radiation toxicity, we hypothesize demographics, pre-treatment tumor characteristics and post-operative complications may also impact radiation toxicities. Materials/Methods An IRB-approved retrospective chart review was performed from 2011-2019 to evaluate patients with posterior uveal melanomas who were treated with brachytherapy at a single institution in the Southeast with a large Hispanic population, with a minimum of 3 months follow-up. We collected patient demographics, pre-treatment tumor characteristics, tumor margin to fovea/optic disk and post-operative complications as potential predictors of RTT. RTT was defined as an event of RM, RNGI, or RON following plaque removal. Univariable analysis (UVA) and multivariable analysis (MVA) were performed using logistic regression model to examine the associations between study variables and the development of RTT. Odds ratios (ORs) and corresponding P-values were reported. All tests were two-sided and statistical significance was considered when P Results A total of 262 patients were evaluated over 8 years. Median follow up was 33.5 months (range 3.02 – 97.31). 178 pts (67.9%) had RTT. 131 pts (50.0%) developed RM. 19 pts (7.3%) developed RNGI. 56 pts (21.4%) developed RO. 41 pts (15.8%) identified as Hispanic. UVA found shorter distance to fovea (OR = 0.97, P = 0.025), post-operative subretinal fluid/exudative retinal detachment (RD) (OR = 2.89, P = 0.002) and vitreous hemorrhage (OR = 3.73, P = 0.002) are associated with RTT and Hispanic ethnicity is not significantly associated with RTT when compared to non-Hispanics (OR = 1.54, P = 0.219). MVA found shorter distance to fovea (OR = 0.95, P = 0.004), post-operative subretinal fluid/exudative RD (OR = 3.14, P = 0.006) and vitreous hemorrhage (OR = 4.50, P = 0.003) are associated with increased RTT. Conclusion These data suggest that shorter distance to fovea and post-operative complications such as subretinal fluid/exudative RD and vitreous hemorrhage are associated with increased risk of RTT. This study can serve as prognostic tools to better counsel patients on the risks and benefits of brachytherapy and allow for early intervention in the management of RTT. These data need to be validated in a prospective trial investigating post-operative complications and subsequent RTT after the treatment of posterior uveal melanomas. Author Disclosure V.A. Peters: None. A. Gurayah: None. D. Kwon: None. W. Zhao: None. W. Jin: Stock; Vit Inc. Partnership; Vit Inc. N.V. Patel: None. A.M. Markoe: None. Z. Correa: None. M.T. Studenski: None. J. Harbour: None. S. Samuels: None.