Objective To quantify the effect of radiotherapy (RT) on urodynamic function 3 months after RT in patients with prostate cancer undergoing definitive external beam RT.
Patients and methods Seventeen patients with clinically localized prostate cancer were accrued into a single-arm prospective study. Sixteen of the patients completed a scheduled multichannel video-urodynamic study at baseline and again 3 months after RT; the urodynamic variables were then compared to assess the nature and extent of urodynamic change caused by RT. Correlations were assessed between these quantitative changes and those in self-assessed qualitative urinary function measured by International Prostate Symptom Score (IPSS), Quality of Life assessment index (QoL) and urinary functional enquiry.
Results There were significant changes detected by the urodynamic study 3 months after RT in bladder volume at capacity (mean decrease 70 mL) and bladder volume at first sensation when supine (mean decrease 85 mL), and a lower postvoid residual volume (mean 50 mL). There was no significant change in the remaining urodynamic variables (including maximum flow rate and voided volume), nor in bladder compliance, bladder instability or bladder outlet obstruction. The self-assessed qualitative urological function measured by the IPSS, QoL and median urinary frequency/24 h showed no significant change after RT.
Conclusions This is the first quantitative study to prospectively evaluate the effect of RT on urodynamics in patients with prostate cancer. Only a few urodynamic variables changed significantly 3 months after RT, while most, including self-assessed qualitative urinary function, did not. This finding corresponds well with the notion that most patients tolerate RT well and that acute RT-induced urinary symptoms resolve successfully, with the return of lower urinary tract function to baseline levels by 3 months after RT.