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Abstract #105747 Published in IGR 23-3
Proton therapy for 166 patients with iris melanoma: side effects and oncological outcome
Gollrad J; Boeker A; Vitzthum S; Besserer A; Heufelder J; Gauger U; Boehmer D; Budach V; Oliver Z; Joussen AMOphthalmology. Retina 2023; 7: 266-274
OBJECTIVES: To investigate the oncological and functional outcomes of a large cohort of patients with a favorable stage of circumscribed and diffuse iris melanoma who underwent primary proton treatment and the risk factors related to initial tumor characteristics and the treatment field architecture. DESIGN: Retrospective, single-center, case study. PARTICIPANTS: We reviewed 225 patients with iris melanoma who were consecutively treated with proton beam therapy at our institution between 1998 and 2020. METHODS: We performed Kaplan-Meier time-to-event analyses and multivariate Cox proportional hazard analyses to identify the impacts of tumor characteristics and target volumes on oncological and functional outcomes. MAIN OUTCOME MEASURES: We measured local tumor control, eye preservation rates, metastasis-free survival, cataract and glaucoma-directed surgery, intraocular pressure, and changes in visual acuity. RESULTS: Of the 192 patients with tumors confined to the iris (T1a-c) who underwent proton therapy as primary treatment, a total of 166 patients (mean age 58.4 years; 88 females) with a minimum follow-up of 6 months were included. Multifocal or diffuse tumor spread was present in 77 (46.4%) patients. The median follow-up time was 54.0 (IQR: 27.4-91.8) months. Local recurrence occurred in 2 patients (1.2%) with circumscribed iris melanoma. Enucleation was a rare event (n=5, 3%) and no patient developed metastatic disease. A large treatment field (full aperture, involving >10 clock hours) was identified as a risk factor for the development of secondary glaucoma (HR: 6.3; p<0.001) and subsequent surgical interventions (HR: 10.85; p<0.001). The large treatment field group showed a significant decline in visual acuity (logMAR >0.3; log-rank p<0.0001), which was associated with secondary glaucoma (HR: 3.40; p=0.002). CONCLUSIONS: Proton therapy provides an effective, non-invasive treatment option for patients with a favorable stage of iris melanoma. Irradiation of the anterior segment up to 10 clock hours is associated with a low risk of the development of secondary glaucoma and vision loss.
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