Rectal morbidity after permanent interstitial brachytherapy for prostate cancer—Impact of Day 1 vs. Day 30 computed tomography–based postimplant dosimetry
Received 16 March 2009; received in revised form 24 April 2009; accepted 28 April 2009. published online 04 September 2009.
Abstract
Purpose
The aim of the study was to evaluate bowel quality-of-life changes after prostate brachytherapy and the impact of Day 1 vs. Day 30 postimplant dosimetry.
Methods and Materials
In 61 patients, computed tomography (CT) scans were performed at Days 1 and 30 after 125I brachytherapy. The patients have been surveyed prospectively before (time A), 1 month (time B), and >1 year after treatment (time C) using a validated questionnaire (Expanded Prostate Cancer Index Composite). Different parameters were tested for their predictive value on bowel quality-of-life changes (bowel bother score decrease >20 points at time B=BB20; bowel bother score decrease >10 points at time C=BC10), including seed displacements.
Results
Mean bowel function/bother score decreased 13/13 points at time B (p<0.01) and 1/4 points at time C (change not significant). BB20 and BC10 were found in 25% and 20% of patients, respectively. Bowel bother score declines at time B correlated well with declines at time C (r=0.53; p<0.01). Prostate volume before implantation and the number of seeds per cubic centimeters were found to be predictive for BB20 and BC10. Smaller rectal wall volumes covered by the 60–100% isodoses at Day 1 were (paradoxically) found to be significantly predictive for BC10. Larger posterior seed displacements between Days 1 and 30 were significantly associated with BB20.
Conclusions
Quality-of-life scores have not been found to change significantly >1 year after brachytherapy. Larger rectal wall volumes within higher isodoses at Day 1 or 30 were not found to be predisposing for adverse quality-of-life changes.
ABSTRACT