You don't, you just measure long term outcomes like mortality in a treatment and control arm. Potentially you have to use a synthetic control.
I am most familiar with NLST which actually was a long term randomized trial.
I am most familiar with NLST which actually was a long term randomized trial.
[edit: or, looking at the NLST you mentioned [1], maybe "treatment" doesn't always mean what I think of as treatment. They are actually comparing two different detection methods, and they aren't using a synthetic control.]
Do they ever use the "survival time after detection" stat I mentioned anymore, or has it been (/ should it be) abandoned?
Yes, NLST was actually a real randomized control trial for lung cancer screening, done before it was known whether or not it was helpful. The trial eventually stopped once they had enough outcome based evidence.
The statistic you mentioned is not used in assessing the effectiveness of screening. It does closely relate to what is though to be the causal mechanism that leads to effectiveness.