Thoughts on 15 year Ascende-RT data?

[DoctwoB]

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https://ascopubs.org/doi/10.1200/JCO.2026.44.7_suppl.306

People have argued against Ascende data on basis of showing a BCR benefit without a survival benefit.

Now at 15 years (with limitations based on data, death attribution, etc), combined therapy is showing a near 50% reduction in PCSM. OS 5% better in combined arm, but not significant. I'd argue showing an OS benefit is near impossible unless the effect size was absolutely massive.

Quick back of the envelope calculation shows to prove significance with a 5% OS benefit with these levels of overall mortality, you'd need around 5,000 deaths and thus a population size of about 12,000.

The final conclusion "Thus, although prostate cancer was the single most common cause of mortality in ASCENDE-RT, our results suggest that even large improvements in b-NED, such as those demonstrated with PB in ASCENDE-RT, are unlikely to improve 15-year overall survival by more than 10% for a population whose median age, performance status, and prognostic variables are similar to ASCENDE-RT participants."

While the statement is true, it also seems written in such a way as to understate the potential benefits. This is talking about the treatment of localized prostate cancer. To say something isnt a big deal since it doesn't meet a 10% OS benefit is ridiculous. Treatment of prostate cancer likely has less then a 10% OS benefit in non high risk disease.

interested to hear the thoughts of the quorum.

 

[OTN]

I have been just as impressed with the 5-year biochemical recurrence-free survival FLAME data as I was with the 5-year ASCENDE-RT data, and it does not come at the cost of significantly increased toxicity.

While I realize cross-trial comparison is not ideal, I've moved to FLAME for my high-risk patients and have been happy with the results.

 

[Aphtalyfe]

I agree with your analysis. I'd only add that the toxicity was higher in the brachy boost arm... but they were doing LDR boost.
The paper seems to be written with bias against brachytherapy... but if you show me these curves and ask me which treatment I want for my patients, myself, or my family members...

 

[WildRivers]

Agree with @OTN . I think FLAME style micro boost is criminally underused. Our practice is brachy heavy and preference is for HDR boost. But, many people don’t want that. I have been getting spacers for FLAME patients - it is really hard to meet 77 Gy < 1cc to rectum.