Surface applicator high-dose-rate fractionated brachytherapy for conservative definitive management of extramammilary Paget’s disease of the penis, scrotum, and mons pubis.

333 Background: This case is of a 70 yo Asian male who had suffered for many years from a painful eroding, oozing, bleeding lesion that started on the mons and over time had spread the full length of the penis and onto the anterior scrotum. A surface mold applicator fractionated computer-optimized high-dose rate (HDR) brachytherapy to 50Gy given in 2 Gy/day 5 days/week for 5 weeks. Methods: For the mons and the anterior scrotum a flat plate of aquaplast was molded with an aperture through which to pass the penis. For the penis a soft wrap, make of two layers of 5mm superflab was created with 15 truguide catheters embedded between. The wrapped penis was then supported with towels and tapes. Using radio-opaque dummy markers a CT was generated and an optimized treatment plan using Oncentra Brachytherapy. Because of the need for daily setups and the intrinsically elastic nature of the penis and scrotum, effort was made to keep the dwell times even so as to minimize any effect from day to day variation in set up. The prescription isodose line was manually adjusted so that where possible there was sparing of deep tissue of the urethra, bladder and testes. When QA was approved the patient began with daily treatments and successfully completed 25 without a treatment break. Results: Sustained local control was observed. Discussion: Surface mold applicator brachytherapy provides the most conformal of radiation therapy to complex superficial targets. For these targets it compares most favorably with all external beam approaches including electron, photon, IMRT and proton therapy. Conclusions: This modality optimally treated these lesions. The depth of the dose can be modulated. The treatment plan can be adapted to deal with swelling late in the course of therapy. The chance of a geographic miss of therapy is low because of the direct application to the affected area.