Highly recommend the episode and show. The gist is that cancer is only 4% of deaths, and screening only reduces those 4% by 20% (so it does not help whatsoever 80% of cancers). But there is a lot more to the episode.
The most important thing you need to do to prevent early death is reduce heart attack and stroke, and that requires better diet and exercise. Really the best drug of all is diet and exercise.
The 4% GP quoted was in reference to individual cancers (since there is no "cancer" screening, each screening is specific to a type of cancer).
I'm having trouble finding numbers, but the comment by Vinay was basically saying that each screening is testing for something that has 1-4% chance of killing you. Not that 4% of all cause mortality is cancer, which is incorrect. In the context of individual screenings per cancer, the numbers roughly make sense based on what I could find, but I am by no means an expert.
I'd highly recommend listening to the Econtalk conversation as there is a lot of nuance behind why screenings (at least as they are done today) could potentially be a net negative at the individual level and don't seem to have improved all-cause mortality in a significant way (according to Vinay).
There are also plenty of screening tests that catch multiple kinds of cancers. But focusing on individual tests misses the forest for the trees. Sure when you look at ever smaller subsets the benefits can seem smaller in each subset, however that’s directly offset by there being more groups.
Critically, these studies are backward looking they can tell you want taking such a test in 2017 followed by getting treatment in 2017 might do, but that doesn’t directly translate to what taking a test in 2024 would be worth.
As to changing all-cause mortality, when you’re talking 8 billion people even moving the needle by a single day represents another 5 years for 4 million people. That’s a big deal.
Treatments for the young tend to move the needle more because the young are likely to live longer. However in the developed world we’ve mostly plucked the low hanging fruit. That’s more or less the definition of a developed country, the obvious routes for development have already happened.
Also cancer screenings happen in the US. Thus 750k deaths without screenings and 80% of that = 600k deaths with screenings and 150k deaths postponed.
Are they using some unusual definition or something?