Prostatic length predicts functional outcomes after iodine-125 prostate brachytherapy.

PURPOSE: To determine the value of prostatic length as a predictor of urinary morbidity after brachytherapy for prostate cancer. METHODS AND MATERIALS: Between May 2002 and September 2008, 214 consecutive patients received brachytherapy for localized prostate cancer at our institution. A prospective analysis of factors predicting urinary toxicity was carried out for these patients. To evaluate urinary morbidity, the posttreatment International Prostate Symptom Score (IPSS) at 3, 9, and 18 months together with rates of urinary retention was recorded. RESULTS: The mean patient age was 62 years, and the mean followup period was 24.4 months. The median IPSS before treatment was 5 (range, 0-20). This increased to 15 (0-33) at 3 months, before subsequently falling to 8 (0-31) and 6 (0-35) at 9 and 18 months, respectively. Twenty-six of 214 (12%) patients experienced urinary retention. Both prostatic length (p-value=0.001, <0.001) and volume (p-value=0.002, <0.001) correlated with a higher posttreatment IPSS at 3 and 9 months. In addition, prostate length and volume predicted those patients developing urinary retention requiring catheterization (p-value <0.001, <0.001). Pretreatment IPSS predicted IPSS at 3, 9, and 18 months (p-value <0.001, <0.001, and 0.011) but did not significantly correlate with retention rates. Other factors predicting IPSS at 3 months included radiation dose (D(90)) (p-value=0.01) and number of needles used (p-value=0.01). CONCLUSION: Prostatic length is a useful tool for determining urinary toxicity after brachytherapy for prostate cancer and should be included in the pretreatment assessment.