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

Abstract

Purpose

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

Design

A single-center, clinical case series.

Participants

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.

Methods

Each tumor was staged according to AJCC criteria and received ⁹⁰Y 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.

Results

High-dose-rate ⁹⁰Y plaque brachytherapy was used to treat small (AJCC cT1) category melanomas. Single-surgery high-dose-rate irradiations were performed under anesthesia. Due to short treatment durations, high-dose-rate ⁹⁰Y 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 ⁹⁰Y treatment durations averaged 8.8 minutes (median 7.9, range 5.8-12.9). High-dose-rate ⁹⁰Y brachytherapy was associated with no periorbital, corneal (Descemet's folds), and/or conjunctival edema. There was no acute or short-term anterior uveitis, secondary cataract, scleropathy, radiation retinopathy, maculopathy, or optic neuropathy. Follow-up was a mean of 16.0 (range 12 to 24) months. Evidence of local control included a lack of expansion of tumor borders (n=6, 100%), darkening and/or 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.

Conclusion

High-dose-rate ⁹⁰Y brachytherapy allowed for single-surgery, minimally invasive, outpatient irradiation of iris and iridociliary melanomas.