The 2023 ASTRO annual meeting included a session on patient-reported quality of life in prostate cancer, featuring a presentation by Dr. Wee Loon Ong discussing a post-hoc analysis of the TROG 03.04 RADAR trial, specifically patient-reported urinary and bowel quality of life outcomes following external beam radiotherapy with or without high-dose-rate brachytherapy boost. Three previous clinical trials have shown that a brachytherapy boost to external beam radiotherapy improves biochemical control.
However, one of the concerns with combining external beam radiotherapy with a high dose rate brachytherapy boost for prostate cancer is increased toxicity, which may be as high as 18%. As such, Dr. Ong and colleagues at ASTRO 2023 aimed to evaluate the long-term urinary and bowel quality of life outcomes following external beam radiotherapy vs external beam radiotherapy + high dose rate brachytherapy boost using data from the TROG 03.04 trial.
Men who had dose-escalated external beam radiotherapy (74 Gy) or external beam radiotherapy (46 Gy) + high dose rate brachytherapy boost (19.5 Gy in 3 fractions) were included in this exploratory analysis of the TROG 03.04 trial [1]. Quality of life outcomes were prospectively collected using the EORTC-QLQ-PR25 at baseline, end of radiotherapy, 12, 18, 24, 36, 60 months, and annually up to 10 years. Quality of life score was normalized to 0-100 with higher scores representing worse symptom burden. Minimal clinically important differences were defined as differences in the respective quality of life scores = 0.5 standard deviations of the baseline quality of life score. Mixed models for repeated measures were used to evaluate longitudinal changes in the quality of life score between external beam radiotherapy and external beam radiotherapy + high dose rate brachytherapy boost arms. Logistic regression was used to evaluate differences in proportion of men with 2x minimal clinically important differences between external beam radiotherapy and external beam radiotherapy + high dose rate brachytherapy boost arms at each time point.
There were 497 men included in this study, including 260 (52%) men that had external beam radiotherapy and 237 (48%) that had external beam radiotherapy + high dose rate brachytherapy boost. The median baseline urinary quality of life scores were 12.5 (IQR 4.2-19.0) and 8.3 (IQR 4.2-20.8) for men in external beam radiotherapy and external beam radiotherapy + high dose rate brachytherapy boost arms respectively (p = 0.5). Within the first 24 months, men in the external beam radiotherapy + high dose rate brachytherapy boost arm had a slower rate of urinary quality of life score resolution compared to men in the external beam radiotherapy arm (p < 0.001). Beyond 24 months, there were no significant differences in the rate of urinary quality of life score resolution between arms:
At 12, 18, 24, and 36 months, men who had external beam radiotherapy + high dose rate brachytherapy boost were 2.4 times (95% CI 1.4-4.0; p < 0.001), 3.1 times (95% CI 1.8-5.1; p < 0.001), 2.8 times (95% CI 1.7-4.7; p < 0.001), and 2.5 times (95% CI 1.4-4.5; p = 0.002) more likely to have 2x minimal clinically important differences in urinary quality of life scores compared to men who had external beam radiotherapy alone:
The median baseline bowel quality of life score was 0 in both arms, and there were no differences in the rate of bowel quality of life score recovery over time between arms:
Men who had external beam radiotherapy + high dose rate brachytherapy boost were less likely to have 2x minimal clinically important differences in bowel quality of life score in the immediate post-radiotherapy period (OR 0.66; 95% CI 0.45-0.97; p = 0.03) and at 60 months (OR 0.51; 95% CI 0.33-0.80; p = 0.003) compared to men who had external beam radiotherapy:
Dr. Ong concluded this presentation discussing a post-hoc analysis of the TROG 03.04 RADAR trial with the following take-home messages:
- External beam radiotherapy + high dose rate brachytherapy boost is associated with greater magnitude of disturbance in urinary quality of life and slower rate of urinary symptom resolution within the first 2-3 years of treatment compared to external beam radiotherapy alone – however, there were no significant differences in urinary symptom score in the long term
- External beam radiotherapy + high dose rate brachytherapy boost is associated with better bowel quality of life symptom score in the immediate post-treatment period, and at 5 years, compared to external beam radiotherapy alone – however, there were no significant differences in bowel symptom score in the long term
- This study provides prospective quality of life data to counsel men on the risk-benefit ratio of external beam radiotherapy + high dose rate brachytherapy boost
Presented by: Wee Loon Ong, MD, BMedSci, MBBS, MPhil (Epi), Alfred Health Radiation Oncology, Melbourne, Australia
Written by: Zachary Klaassen, MD, MSc – Urologic Oncologist, Associate Professor of Urology, Georgia Cancer Center, Wellstar MCG Health, @zklaassen_md on Twitter during the 2023 American Society of Radiation Oncology (ASTRO) Annual Meeting, San Diego, CA, Sun, Oct 1 – Wed, Oct 4, 2023.
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