Preservation of visual acuity after eye-sparing ruthenium-106 brachytherapy in choroidal melanoma patients

ESTRO 2024 Congress report

Ruthenium-106 brachytherapy is an effective treatment for choroidal melanoma, the most prevalent primary ocular malignancy in adults. This treatment limits the radiation dose to organs at risk and spares visual acuity.

To assess treatment efficacy and visual acuity outcomes, we investigated a retrospective cohort of 412 choroidal melanoma patients who were treated subsequently between 2012 and 2016 at Leiden University Medical Center in Leiden, The Netherlands. Treatment eligibility criteria were a tumour prominence of ≤7mm and diameter of ≤16mm with a favourable location (in juxtapapillary tumours, which are close to the optic nerve, plaque placement is technically more difficult). During this period, patients with larger or unfavourably located tumours were offered either international referral for proton beam therapy, which was not yet available in The Netherlands, or enucleation if patients were unwilling or unable to travel. As a result, some patients with borderline-sized or unfavourably located tumours were treated with ruthenium-106 brachytherapy.

The five-year overall survival rate (82%) risk of and metastases (12%) were favourable, probably due to patient selection. The five-year eye retention rate was 95%. We found a high five-year local control probability of 92%. Patients with juxtapapillary tumours had a higher five-year risk of local failure (20%) compared with patients with non-juxtapapillary tumours (6%, p<0.001).

Retention of visual acuity is one of the most important outcomes for patients. The risk of lasting severe visual impairment (Snellen visual acuity <0.1) after five years was 31%. A multivariable Cox-regression analysis with predefined covariates showed a significant impact on this risk of pre-treatment visual acuity, patient age, tumour location and scleral dose. In central tumours, in which dose to the macula and optic nerve is often unavoidable, the five-year risk of severe visual impairment was 50%, compared with 12% (p<0.001) in (mid)peripheral tumours.

In conclusion, ruthenium-106 brachytherapy is a safe and effective treatment for small to intermediate-sized uveal melanomas. In juxtapapillary tumours, plaque placement and the achievement of adequate target coverage are technically more difficult. These tumours are associated with a higher risk of local failure, and this strengthens the case for treatment of these tumours with proton beam therapy. Ruthenium-106 brachytherapy yields favourable visual acuity outcomes, especially in tumours that are not close to the macula or optic nerve.

Lennart Pors is a medical doctor pursuing his PhD in the Department of Radiation Oncology at Leiden University Medical Center. In collaboration with the Departments of Radiology and Ophthalmology, he works on MRI-based eye modelling for treatment planning and on treatment toxicity-risk prediction.

Lennart Pors

Departments of Radiation Oncology and Ophthalmology, Leiden University Medical Center, Leiden, The Netherlands.

l.j.pors@lumc.nl

https://www.linkedin.com/in/lennartpors/

https://mreye.nl/

Award ceremony 

left to right: Evert van Limbergen, Lennart Pors, Maarten ter Mors, Head of Brachy Solutions Elekta