It takes (point) two.
Top Line: Brachytherapy has strikingly different radiobiologic effects on prostate cells than external beam photons, so maybe it deserves a different prostate-specific antigen (PSA) threshold for biochemical failure.
The Study: After all, urologists and rad oncs use two very different thresholds following their respective definitive therapies: an absolute value of 0.2 ng/mL in the first case and 2.0 ng/mL above nadir in the second. While there’s good reason for this—namely that external beam radiation leaves behind normal PSA-producing cells and surgery shouldn’t—the differing rules add another dimension of complexity in any attempt to compare biochemical control across treatment modalities. So in which category should brachy fall? Enter this reanalysis of the ASCENDE-RT trial in which patients with intermediate and high risk prostate cancer were randomized to dose-escalated prostate radiation with external beam versus brachy. As expected, re-defining failure from ≥2.0+nadir → >0.2 ng/ml murdered biochemical control rates at 9 years in the external beam arm from 63 → 31%. Shockingly, though, rates in the brachy arm were virtually indistinguishable at 85 → 82%. Wow.
Bottom Line: These authors, albeit in the “Brachytherapy” journal, suggest biochemical control of prostate cancer following brachy versus surgery can now be better compared, with brachy clearly reigning victorious. | Morris, Brachytherapy 2018
The Study: After all, urologists and rad oncs use two very different thresholds following their respective definitive therapies: an absolute value of 0.2 ng/mL in the first case and 2.0 ng/mL above nadir in the second. While there’s good reason for this—namely that external beam radiation leaves behind normal PSA-producing cells and surgery shouldn’t—the differing rules add another dimension of complexity in any attempt to compare biochemical control across treatment modalities. So in which category should brachy fall? Enter this reanalysis of the ASCENDE-RT trial in which patients with intermediate and high risk prostate cancer were randomized to dose-escalated prostate radiation with external beam versus brachy. As expected, re-defining failure from ≥2.0+nadir → >0.2 ng/ml murdered biochemical control rates at 9 years in the external beam arm from 63 → 31%. Shockingly, though, rates in the brachy arm were virtually indistinguishable at 85 → 82%. Wow.
Bottom Line: These authors, albeit in the “Brachytherapy” journal, suggest biochemical control of prostate cancer following brachy versus surgery can now be better compared, with brachy clearly reigning victorious. | Morris, Brachytherapy 2018
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