Do patients with larger prostates have greater toxicity after external beam radiotherapy for localized prostate cancer?

Abstract

15577 Background: To aim of the study was to assess the impact of prostate volume (PV) on health-related quality of life (HRQOL) before and at different points in time after conformal radiotherapy for prostate cancer. Methods: A group of 180 patients has been surveyed prospectively before (time A), at the last day (B), two months after (C) and sixteen months (median) after (D) radiotherapy (70.2- 72Gy) using a validated questionnaire (Expanded Prostate Cancer Index Composite). Patients in this analysis (n=165) met the prerequisite of responding to the first and last questionnaire. The multi-item scale scores were transformed lineary to a 0–100 scale, with higher scores representing better HRQOL. The group has been divided into a subgroup with a small PV (median 32cc; range 11–45; 83 patients) and a subgroup with a large PV (median 59cc; range 46–151; 82 patients). Results: Treatment plans for large prostates implied a larger planning target volume (averagely 396 vs. 305cc; p<0.01) with a significantly larger dose to the bladder and rectum at all volume levels. Patients with large prostates presented with lower urinary bother (averagely 76 vs. 83; p=0.04), but higher bowel bother scores (averagely 95 vs. 90; p<0.01) before the beginning of treatment. At time B, urinary bother scores decreased stronger for patients with large prostates (averagely 22 vs. 16 points). Comparing posttreatment scores to baseline scores, no significant decrease resulted for urinary function or bother scores for both groups at time C and D. At time D, urinary function scores even increased significantly for patients with large prostates (averagely 4 points). Bowel function and bother scores were still significantly lower for both groups at time C and D (averagely 3–8 points). HRQOL scores did not differ significantly between both patient groups at time D. Conclusions: In spite of a higher dose-load to the organs at risk, lower urinary bother scores before treatment and a higher decrease of urinary scores at the end of radiotherapy for patients with larger prostates, long-term HRQOL scores did not differ significantly between patients with large and small prostates. An improvement of urinary function suggests a regression of hyperplastic prostatic tissue. No significant financial relationships to disclose.