«Respectfully, the 15 year life expectancy numbers are not a one size fits all deal for everyone with prostate cancer.»

That's a good reminder. Almost all studies use "overall survival" (OS) as their measure, since it's hard to tell exactly what eventually kills someone. I expect that OS understates actual life expectancy for younger people, and overstates it for older ones (e.g. if you're already 95, you're probably not going to make 110 regardless of how your prostate cancer progresses, but please prove me wrong!).

However, the biggest issue is that all studies are backwards looking, often using data that they started collecting 10–20 years ago (even if the study came out recently), and so much has changed in Prostate Cancer treatments and best-practices in the last 5–6 years that perhaps all of the numbers are inapplicable now. We're the new sample population, and new studies like IRONMAN will some day tell us what's happening to us today.