Innovative and Customized 3-Dimensional-Printed Mold Brachytherapy Treatment of Genital Extramammary Paget's Disease

Extramammary Paget's disease (EMPD) is a rare intraepithelial neoplasm that affects apocrine gland-rich areas of the perineal region. Surgical treatment is the standard of care but is associated with significant morbidity. Nonsurgical options, such as surface mold brachytherapy (SMBT) with custom 3-dimensional (3D)-printed applicators, offer an innovative, organ-preserving alternative. Our aim was to evaluate the efficacy, safety, and cosmetic outcomes of custom 3D-printed SMBT in patients diagnosed with EMPD.

A retrospective case series involving 9 patients treated for EMPD between November 2019 and April 2023 was included. Patient demographics, clinical characteristics, treatment parameters, and outcomes were analyzed. Primary outcomes included clinical response rates, acute and late toxicities (graded according to the National Cancer Institute Common Terminology Criteria for Adverse Events, version 5), and patient-reported cosmetic outcomes.

All 9 patients (6 men and 3 women) achieved a complete clinical response, with 1 patient experiencing marginal recurrence at 13.6 months posttreatment. Acute grade 3 dermatitis occurred in all patients and resolved, on average, within 54 days (range, 35-72). Late toxicities included hypopigmentation (4 patients) and telangiectasia (3 patients). Cosmetic outcomes were rated as excellent or very good by 89% of patients.

This study represents the first report on the use of custom 3D-printed SMBT for EMPD. This technique demonstrates excellent local control, manageable toxicity, and favorable cosmetic outcomes, offering a promising alternative to surgery in this anatomically complex area.