Rectal morbidity after permanent interstitial brachytherapy for prostate cancer--impact of day 1 vs. day 30 computed tomography-based postimplant dosimetry.
OBJECTIVE
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
In 61 patients, computed tomography (CT) scans were performed at Days 1 and 30 after (125)I 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.
Pinkawa
Michael
M
Department of Radiation Oncology, RWTH Aachen University, Pauwelsstrasse 30, Aachen, Germany. MPinkawa@ukaachen.de
Piroth
Marc D
MD
Holy
Richard
R
Klotz
Jens
J
Nussen
Sandra
S
Borchers
Holger
H
Heidenreich
Axel
A
Eble
Michael J
MJ
D001918:Brachytherapy / Q000009:adverse effects*; D006801:Humans; D008297:Male; D011446:Prospective Studies; D011471:Prostatic Neoplasms / Q000150:complications / Q000000981:diagnostic imaging / Q000532:radiotherapy*; D011788:Quality of Life; D011832:Radiation Injuries / Q000000981:diagnostic imaging / Q000209:etiology*; D011874:Radiometry; D011879:Radiotherapy Dosage; D012002:Rectal Diseases / Q000000981:diagnostic imaging / Q000209:etiology*; D018570:Risk Assessment / Q000379:methods; D012307:Risk Factors; D014057:Tomography, X-Ray Computed / Q000706:statistics & numerical data; D016896:Treatment Outcome