If I used to smoke, should I get the yearly CT scan for lung cancer?

Both are talking about the same people, adults roughly 50 to 80 who smoke or used to smoke heavily, which is unusual and is what makes this a real disagreement rather than two answers to different questions.

Neither is talking about someone who has never smoked, and neither is talking about a scan ordered because of a symptom. Prasad is addressing the person about to say yes at the appointment; the American Cancer Society is addressing the whole eligible population and what the health system should offer it.

More than the headline suggests. Both accept that the scan finds early lung cancers, both send the decision to a conversation with a clinician rather than a rule, and both treat stopping smoking as the larger prize.

The disagreement is about what the trials proved and how much of it should be said out loud: whether finding cancers earlier has been shown to leave people alive longer overall, and whether the harms of the follow-up belong in the same sentence as the benefit.

For Prasad: a published analysis from the existing trials showing what screening did to the treatment people received, smaller operations, fewer chest tubes, less chemotherapy, or a trial showing fewer deaths from any cause. He says so in as many words and asks readers to send him the paper if it exists.

For the American Cancer Society: the guideline is revised on a schedule against new trial evidence, so a large trial reporting no benefit on deaths from any cause, or better data on the harms of following up what the scan finds, is what would move it.