[killjoywashere]

> I think you’re thinking about circulating tumor cells

No, I'm very clear on ctDNA, cell-free DNA, whatever you want to call it.

My point stands: early detection goes back to in situ lesions.

The first problem is finding in situ lesions, which is hard.

The second problem is the amount of fear-induced care this generates. These tests are screening tests, so the vendors will lower their operating points to get their false-negative rates down, which will drive up fear, which will drive up follow-on testing, which will drive up follow-on treatment. How much is what matters.

US healthcare costs are already astronomical to the point of becoming a national security problem. And you want to spend more?

[doctoring]

Your original comment stated:

> They won't work for in situ tumors, almost by definition.

Which isn't true. The studies from multiple companies' tests demonstrate that they _can_ detect in situ tumors. Not always super duper well, and not always for every single cancer type, but still.

Whether this is a good idea / cost-effective is another question, and certainly a big deal as you point out.