You explain things so simply and clearly. Kudos!
One question, though. I understand when you say in general that CT scans for lung cancer screening can be dangerous. Excess radiation exposure, incidentalomas, cost, etc. I get it. But for those occasions when someone gets a lung tumor discovered early, don’t you think the screening is actually worth it? I mean, how can finding cancer earlier NOT prolong life?
Paula from Paducah
Good question. Two related answers.
Simply defined, lead-time bias gives a the false impression of prolonged life, because the time of diagnosis occurs earlier. But in diseases for which the treatment we have doesn’t alter the course of the illness (like lung cancer), we do not actually prolong life. So the “early” diagnosis is in fact an artifact.
Reason 2 is that lung cancer discovered on screening CTs is usually too far advanced to make early treatment meaningful in terms of survival benefit. Put another way, even if you know earlier that you have the illness, it doesn’t make a difference (in aggregate) for people with the disease.
This stuff is hard because if you’re the one (or you have a family member or friend) with the disease, it seems logical that it HAS to make a difference to find the information sooner rather than later.
Sadly, at this point, it’s just not true.