Long-Term Quality of Life in Prostate Cancer Patients Treated with Cesium-131

Abstract

Prostate brachytherapy (PB) as monotherapy or in combination with external beam radiotherapy (EBRT) represents a curative treatment option for men with prostate cancer. Several radioactive isotopes are approved for use in prostate brachytherapy. Among these, Cesium-131 is the newest to market and has the shortest half-life, a property which gives it dosimetric advantages. Little data exists as to the long-term quality of life (QoL) in patients treated with Cs-131. We identified the first 272 patients treated at our institution with Cs-131, all of whom were treated greater than 5 years ago. Patients were treated between September 2006 and October 2010. These patients were asked to fill out an Expanded Prostate Cancer Index Composite (EPIC) QoL questionnaire and American Urological Association Symptom Score (AUASS) survey before treatment and at each of their follow-up appointments. EPIC scores were reported on a normalized scale from 0-100 (with higher score representing better QoL) for the following categories: Urinary Summary (US), Urinary Function (UF), Urinary Bother (UB), Urinary Incontinence (UI), Urinary Irritation/Obstruction (UIO), Bowel Summary (BS), Bowel Function (BF), and Bowel Bother (BB). AUA scores were reported on a scale of 0-35 (with higher scores representing worse symptomatology). We compared patients’ EPIC and AUA scores at baseline to those at 5-yrs post-treatment. Mean scores were compared using a paired-samples t-test. Clinically significant improvement or worsening in QoL was defined as a change of 10 or more points in EPIC score or 3 or more in AUA score. At 5-yrs of follow-up, 129 patients (47%) had completed both EPIC and AUA questionnaires and one additional patient completed AUA only. Of these 130 patients, median age was 65 (Interquartile range =61-71), 28% had EBRT prior to PB, risk groups were: 40% low-risk; 51% intermediate-risk; 9% high-risk, and 18% received hormonal therapy. Baseline mean EPIC scores were as follows: US=86.7, UF=93.5, UB=82.0, UI=90.8, UIO=85.9, BS=91.5, BF=92.2, BB=90.8. Baseline mean AUA score was 6.9. Average changes in scores at 5-yrs were as follows: US=0.30 (p=0.78), UF=-1.33 (p=0.20), UB=1.51 (p=0.28), UI=-3.25 (p=0.02), UIO=1.98 (p=0.08), BS=-0.07 (p=0.94), BF=-0.26 (p=0.77), BB=-0.11 (p=0.93), AUA=0.18 (p=0.72). The percent of patients with a clinically significant worsening of symptomatology were: US=18%, UF=19%, UB=22%, UI=24%, UIO=14%, BS=13%, BF=16%, BB=17%, AUA=30%. The percent of patients with a clinically significant improvement of symptomatology were: US=15%, UF=14%, UB=27%, UI=15%, UIO=21%, BS=16%, BF=15%, BB=19%, AUA=26%. Our results demonstrate minimal long-term urinary or bowel toxicity with Cs-131 prostate brachytherapy. There were no significant long-term differences in EPIC Urinary Summary score, EPIC Bowel Summary score, or AUA symptom score. As population-based means tend to underestimate individual effects, our conclusion is further validated by the small absolute difference in the rates of clinical improvement and worsening (<10% for all variables).