# Anatomical outcome after brachytherapy with bi-nuclide (Ru-106/Iodine-125) plaques in large uveal melanomas

## TL;DR

A new brachytherapy method using combined radioactive sources improves eye retention and tumor control in large uveal melanoma patients.

## Contribution

Demonstration of bi-nuclide plaques' effectiveness in treating large uveal melanomas with improved eye retention and tumor control.

## Key findings

- 86.5% of patients retained their eye 2.5 years after treatment with bi-nuclide plaques.
- Higher age, tumor thickness, and visual acuity were independently associated with increased risks of enucleation and tumor recurrence.
- Bi-nuclide plaques delivered higher target doses while reducing dose to surrounding structures compared to traditional methods.

## Abstract

Proprietary bi-nuclide plaques combine the radiation properties of beta and gamma brachytherapy and can irradiate a larger target volume compared to ruthenium-plaques. While reducing the dose to structures outside the target volume, brachytherapy with bi-nuclide-plaques (BBNP) delivers a higher target dose compared to iodine-plaques. We aimed at analyzing the local tumor control and eye retention probability after BBNP.

All consecutive cases with large uveal melanoma (tumor thickness ≥ 7 mm) treated with BBNP at our institution between 01/1999 and 12/2020 were included (n = 576, median follow-up: 30.8 months [interquartile range, IQR: 12.9–57.4]). Univariable and multivariable Cox regression analyses were performed.

Secondary enucleation (SE) was performed in 13.5% of cases (n = 78) after the median of 20.0 months (IQR: 9.0–34.7) post-BBNP. The overall rate of local tumor recurrence (LR) in the cohort was 8.5% (n = 49) and was diagnosed at the median post-BBNP interval of 20.0 months (IQR: 15.6–35.2). Of the patients’ baseline characteristics, higher age (> 67 years, adjusted hazard ratio [aHR] = 1.80, p = 0.011), tumor thickness (> 8.5 mm, aHR = 2.20, p = 0.002), visual acuity (> 0.5 logMAR, aHR = 1.83, p = 0.009), and sclera dose (> 1000 Gy, aHR = 1.65, p = 0.034) were independently associated with the risk of SE. In turn, higher age (> 67 years, aHR = 1.93, p = 0.023), tumor thickness (> 8.5 mm, aHR = 2.02, p = 0.020), and visual acuity (> 0.5 logMAR, aHR = 2.27, p = 0.005) were independently related to LR.

BBNP facilitates eye retention in 86.5% of patients with large uveal melanoma 2.5 years after treatment. Patients’ baseline, tumor and treatment characteristics were strongly associated with the risk of SE and LR after BBNP.

The online version contains supplementary material available at 10.1186/s13014-025-02707-7.