Risk factors for the development of prostate brachytherapy related urethral strictures

PURPOSE: We identified clinical, treatment and dosimetric parameters associated with the development of urethral strictures following permanent prostate brachytherapy. MATERIALS AND METHODS: From April 1995 through April 2003, 1,186 consecutive patients underwent prostate brachytherapy for clinical stage T1b-T3a NxM0 (2002 American Joint Committee on Cancer) prostate cancer. The treatment plan included supplemental XRT in 625 patients (52.7%) and androgen deprivation therapy in 465 (39.2%). Median followup was 4.3 years. Multiple clinical, treatment and dosimetric parameters were evaluated in univariate and multivariate analyses to identify independent predictors for urethral stricture disease. RESULTS: A total of 29 patients had brachytherapy related urethral strictures. All strictures involved the BM urethra with a 9-year actuarial risk of 3.6% and a median time to development of 2.4 years. The mean radiation dose to the BM urethra was significantly greater in patients with vs without stricture (p = 0.002). On multivariate analysis the BM urethral dose and supplemental XRT predicted urethral stricture. All except 3 patients were successfully treated with urethral dilation or internal optical urethrotomy. CONCLUSIONS: Brachytherapy related urethral stricture disease correlates highly with the radiation dose to the BM urethra. Careful attention to brachytherapy preplanning and intraoperative execution along with the judicious use of supplemental XRT is essential to minimize the incidence of stricture disease.