Prostate cancer: extended androgen suppression slows disease progression in long-term

  • Joseph D & al.
  • Int J Radiat Oncol Biol Phys
  • 26 Feb 2020

  • curated by Deepa Koli
  • Univadis Clinical Summaries
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Takeaway

  • 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.

Study design

  • 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.

Key results

  • 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).

Limitations

  • Radiation dose not randomized.