- In prostate cancer, 18 months of androgen suppression (AS) significantly reduced distant progression vs 6 months, independent of radiotherapy (RT) dose in this long-term follow-up analysis.
- High-dose-rate brachytherapy boost (HDRB) achieved superior outcomes independent of AS duration in post hoc subgroup analysis.
Why this matters
- Superior oncologic outcomes with HDRB vs dose-escalated external beam RT (EBRT) need confirmation in a randomized trial.
- 10-year follow-up of TROG 03.04 RADAR trial: 1051 patients with locally advanced prostate cancer, randomly allocated to 6- or 18-month AS with radiotherapy.
- Radiotherapy dosing: 66-, 70-, or 74-Gy EBRT, or 46-Gy EBRT+HDRB.
- Funding: National Health and Medical Research Council, Australia.
- After adjustment for radiation dose, 18-month AS significantly reduced risk for distant progression:
- Sub-HR (sHR), 0.70 (P=.002).
- No interaction was observed between AS duration and RT dose (P=.76).
- 18-month AS significantly reduced distant progression (sHRs) with:
- 70-Gy: 0.67 (P=.039).
- HDRB: 0.61 (P=.036).
- HDRB significantly reduced distant progression (sHR, 0.68; P<.0001 independent of as duration.>
- Independent reduction in risk (sHR) for:
- Local progression: 0.60 (P=.03) with 18-month AS and 0.28 with HDRB (P<.0001>
- Bone progression: 0.62 (P=.0001) and 0.63 (P=.0004).
- Cancer-specific mortality: 0.70 (P=.009) and 0.65 (P=.0004).
- Radiation dose not randomized.