LA-PCa: 18-month ADT offers survival advantage in RADAR

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Takeaway

  • Intermediate-term (18 months) androgen deprivation therapy (ADT) shows superiority vs short-term (6 months) treatment in patients with locally advanced prostate cancer (LA-PCa) treated with radiotherapy.
  • Add-on zoledronic acid shows no added benefit.

Why this matters

  • The optimal ADT duration in the curative management remains unclear.

Study design

  • Randomized, phase 3, 2 × 2 factorial RADAR study: 1071 patients with LA-PCa who received radiotherapy were treated with either 6 or 18 months of ADT, with or without zoledronic acid.
  • Funding: National Health and Medical Research Council of Australia.

Key results

  • Median follow-up, 10.4 years.
  • No interactions were identified between ADT and zoledronic acid, therefore groups were collapsed to 6-months ADT and 18-months ADT.
  • 10-year cumulative incidence of cancer-specific mortality was higher for 6 vs 18 months ADT (13.3% vs 9.7%; sub HR [sHR], 0.70; P=.035).
  • No difference was observed in all-cause mortality.
  • 6- vs 18-month ADT was associated with higher cumulative incidences of:
    • Distant progression: 27.5% vs 20.7% (sHR, 0.71; P=.0044).
    • Local progression: 7.9% vs 4.9% (sHR, 0.61; P=.022).
    • PSA progression: 45.9% vs 34.0% (sHR, 0.65; P<.0001>
  • Add-on zoledronic acid had no effect on oncologic outcomes.
  • Overall 12 cases of osteonecrosis were reported (3 with zoledronic acid).

Limitations

  • Open-label design.