Re:Cheap blood test detects pancreatic cancer before it spreads
by mlyle on Friday February 14, 2025 @09:53AM
(#43048910)
> I'm confused. If this blood test gave a false positive that wasn't due to an anomaly in the blood itself,
That's the errant part. A small amount of the false positives will be because of lab issues. The rest will be because this patient is different in some way, but not all of them are cancer. Medicine doesn't have very many perfectly specific tests.
So you have a patient who has some weird enzymes around because they're genetically different, for example, and they always pop positive on this particular test. Or has an unusual diet that causes some other non-tested-for-enzyme level to be high enough to set off this sensor. Or whatever.
In this case, the specificity is 98%, so this false positive rate is about 2%.
That's the errant part. A small amount of the false positives will be because of lab issues. The rest will be because this patient is different in some way, but not all of them are cancer. Medicine doesn't have very many perfectly specific tests.
So you have a patient who has some weird enzymes around because they're genetically different, for example, and they always pop positive on this particular test. Or has an unusual diet that causes some other non-tested-for-enzyme level to be high enough to set off this sensor. Or whatever.
In this case, the specificity is 98%, so this false positive rate is about 2%.