Optimized penile surface mold brachytherapy using latest stereolithography techniques: A single-institution experience.

PURPOSE To describe a technique of penile surface mold high-dose-rate (HDR) brachytherapy and early outcomes. METHODS AND MATERIALS Five patients diagnosed with a T1aN0 squamous cell carcinoma of the penis were treated using a penile surface mold HDR brachytherapy technique. A negative impression of the penis was obtained using dental alginate. CT images were acquired of the penile impression; subsequently, a virtual model of the patient's penis was generated. The positive model was imported into a computer-assisted design program where catheter paths were planned such that an optimized offset of 5 mm from the penile surface was achieved. The virtual model was converted into a custom applicator. A total dose of 40 Gy was delivered in 10 fractions. Patients were followed at 1, 3, 6, and 12 months after treatment and then every 6 months thereafter. Toxicities were reported using Common Terminology Criteria for Adverse Events v4.0. RESULTS All patients tolerated treatment well. Acute Grade 2 skin reactions were observed within the first month after treatment. Median followup was 35 months. Late Grade 1 skin toxicities were observed. One patient experienced a urethral stricture requiring dilatation. Two patients developed local recurrence. CONCLUSION This technique allows the delivery of penile HDR brachytherapy as an outpatient procedure with minimal discomfort to the patient during each application and is a repeatable and accurate setup. This technique warrants validation in larger series with longer followup.