1046 poster URETHRAL STRICTURE AS A COMPLICATION OF HIGH DOSE RATE BRACHYTHERAPY FOR PROSTATE CANCER

Abstract

Purpose: Urethral stricture is one of the well-known complications of treatment for prostate cancer, regardless of the particular type of therapeutic modality. The goal of our study was to determine the incidence, timing, and outcomes of urethral strictures in the cohort of patients undergoing high dose rate (HDR) brachytherapy for prostate cancer. Materials: A retrospective review of 360 consecutive patients undergoing HDR brachytherapy at our institution from 1997-2009 was performed. Among the 360 patients, 158 patients had high risk prostate cancer, 187 patients had intermediate risk prostate cancer, and 15 patients had low risk prostate cancer. Three hundred thirty-six patients (93%) received neo-adjuvant hormone therapy. The HDR protocol typically called for 3 treatment sessions over a period of 24 hours in 2 days. A single radioactive iridium-192 source was used with a nominal activity of 370 GBq. The peripheral minimum dose to the prostate gland per session was 6 Gy. All patients received supplementary external beam radiation therapy after completion of the brachytherapy procedure, and external beam dose ranged from 45 Gy to 50.4 Gy (median 50 Gy) using conventional fractionation schemes. Twenty patients were lost to follow up or had insufficient follow up and were excluded from analysis. All urethral strictures were diagnosed cystoscopically. Patient demographics, operative, and postoperative data were reviewed. Results: Three hundred thirty-nine patients were analyzed with an overall survival rate of 98.6%, at a mean follow-up of 55 months. Two patients died from metastasis and 2 other patients died from unrelated causes. Two hundred eighty-two patients (83.1%) are currently free of disease or biochemical progression. Twenty-two patients (6.5%) have developed urethral strictures to-date. The median time between radiation therapy and the diagnosis of urethral stricture was 4 years (range 1-8 years), with nearly all strictures located in the bulbomembranous urethra. At last follow-up, 2 patients had a stable, patent urethra. One of these patients was managed with single balloon dilation, while the other patient underwent urethroplasty after failing endoscopic management. The remaining 20 patients did not have a stable patent urethra. Nine (41%) of these patients required a urethral dilation schedule, and 3 patients (14%) needed either suprapubic tube or urethral catheter drainage. Five patients (23%) have required multiple endoscopic procedures or dilations (range 2-7), while 3 patients (14%) have required dilation at last follow-up. Conclusions: Urethral stricture incidence from HDR brachytherapy in combination with external beam radiotherapy for clinically localized prostate cancer is 6.5%. Although radiation induced urethral stricture has a relatively low incidence, it could result in significant morbidity for the patient. Short term data supports HDR brachytherapy as an equivalent therapy for localized prostate cancer, but should be limited to high volume centers to minimize refractory urethral stricture complications.