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.