Is there a relation between the radiation dose to the different sub-segments of the lower urinary tract and urinary morbidity after brachytherapy of the prostate with I-125 seeds?

Background and purpose: To investigate possible relationships between the dose to the sub-segments of the lower urinary tract and lower urinary tract symptoms (LUTS) after brachytherapy of the prostate.

Materials and methods: This study involved 225 patients treated for prostate cancer with I-125 seeds. Post-implant dose-volume histograms of the prostate, urethra, bladder wall, bladder neck and external sphincter were determined. Endpoints were the mean and the maximum International Prostate Symptom Score (IPSS) during the first 3months after the treatment. For binary analysis the patients were stratified in a group with enhanced LUTS and a group with non-enhanced LUTS.

Results: The dose to 0.5cm(3) of the bladder neck 'D0.5cc-blne' (p=0.002 and p=0.005), the prostate volume prior to treatment 'Vpr-0' (p=0.005 and p=0.024) and the pre-treatment IPSS (both p<0.001) were independently correlated with mean and maximum IPSS, respectively. Of the patients with a D0.5cc-blne⩾175Gy and a Vpr-0⩾42cm(3), 68% suffered from enhanced LUTS, against just 30% of the other patients (p<0.0001).

Conclusions: Pre-treatment IPSS, prostate volume and dose to the bladder neck are correlated with post-implant IPSS. A combination of a large prostate and a high dose to the bladder neck is highly predictive for enhanced early LUTS.