High-Dose-Rate Yttrium-90 (⁹⁰Y) Episcleral Plaque Brachytherapy for Iris and Iridociliary Melanoma

To describe a pilot study on the use of single-session, high-dose-rate, Food and Drug Administration-cleared, yttrium-90 (Y⁹⁰) plaque brachytherapy for iris and iridociliary melanoma.

A single-center, clinical case series.

Six consecutive patients were included in this study. Each was diagnosed with an iris or iridociliary melanoma based on clinical examination with or without biopsy.

Each tumor was staged according to the American Joint Committee on Cancer criteria and received Y⁹⁰ eye plaque brachytherapy. The main variables were tumor size, patient age, sex, and method of diagnosis (clinical or biopsy). Surgical techniques, treatment durations, and ocular side effects were recorded. Local control was defined as a lack of tumor growth or regression determined by clinical examinations, including slit-lamp and gonio photography, as well as high-frequency ultrasound measurements. Toxicity parameters included acute and short-term corneal/scleral change, anterior segment inflammation, and cataract progression.

Local and systemic cancer control, tumor regression, visual acuity, as well as radiation-related normal tissue toxicity.

High-dose-rate Y⁹⁰ plaque brachytherapy was used to treat small (American Joint Committee on Cancer cT1) category melanomas. Single-surgery high-dose-rate irradiations were performed under anesthesia. Because of short treatment durations, high-dose-rate Y⁹⁰ did not require the additional procedures used for low-dose-rate plaque (e.g., sutures, amniotic membrane epicorneal buffering, Gunderson flaps, and second surgeries for plaque removal). Only conjunctival recession was used to avoid normal tissue irradiation. High-dose-rate Y⁹⁰ treatment durations averaged 8.8 minutes (median, 7.9; range, 5.8-12.9). High-dose-rate Y⁹⁰ brachytherapy was associated with no periorbital, corneal (Descemet folds), or conjunctival edema. There was no acute or short-term anterior uveitis, secondary cataract, scleropathy, radiation retinopathy, maculopathy, or optic neuropathy. The follow-up was a mean of 16.0 (range 12-24) months. Evidence of local control included a lack of expansion of tumor borders (n = 6, 100%), darkening with or without atrophy of the tumor surface (n = 5/6, 83%), and a mean 24.5% reduction in ultrasonographically measured tumor thickness. There were no cases of metastatic disease.

High-dose-rate Y⁹⁰ brachytherapy allowed for single-surgery, minimally invasive, outpatient irradiation of iris and iridociliary melanomas.

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