The impact of radiation dose to the urethra on brachytherapy-related dysuria

Abstract

Purpose To determine the effect of urethral dose on dysuria after permanent prostate brachytherapy. Methods and materials One hundred eight patients without a preimplant history of a transurethral resection underwent brachytherapy on one of two prospective randomized trials for clinical T1c–T2c (2002 AJCC) prostate cancer. Urethral dose was stratified into cohorts of <150% and ⩾150% minimum peripheral dose (mPD) respectively. No patient received prophylactic alpha blockers. The median follow-up was 27.4 months. Dysuria was defined as pain and/or burning on urination and was evaluated on a 0–10 scale. Normalization of dysuria was defined as a return to within 1 point of baseline. Dysuria surveys were obtained before brachytherapy and at 1, 3, 6, and 12 months after implantation. Clinical, treatment, and dosimetric parameters evaluated included urethral dose, age, preimplant International Prostate Symptom Score (I-PSS), ultrasound volume, hormonal status, supplemental XRT, isotope, V 100/200, D 90, the maximum post-implant I-PSS, and the time to I-PSS resolution. Results The incidence of dysuria peaked at 85% one month after brachytherapy with subsequent resolution over time. Radiation dose to the urethra (stratified into cohorts of <150%, and ⩾150% mPD) was not a significant predictor of prevalence, severity, or resolution of dysuria. In a multivariate analysis, isotope predicted for dysuria normalization while preimplant I-PSS and D 90 predicted for maximum dysuria; however, the area under the ROC curve and the Pearson correlation coefficient revealed weak correlations. Conclusions Dysuria is common after brachytherapy, but typically minimal in severity. Urethral doses did not predict for either dysuria severity or normalization. Although preimplant I-PSS was the strongest predictor of maximum dysuria and isotope the best predictor for dysuria normalization, robust predictors for brachytherapy-related dysuria were not identified.