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New blood test could detect more than 20 types of cancer

telegraph.co.uk

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Re: New blood test could detect more than 20 types of cancer

#31

Post by sandworm101 »

killjoywashere wrote: post #27
sandworm101 wrote: post #10

Earlier quoted context omitted.

It seems to have a great false positive rate, but a not-good false negative rate. It misses the bulk of stage one cancers. So its utility for early diagnosis (the important bit) is marginal at this time.

For those not in the lab business: a low false positive rate and a high false negative rate are useful for confirmatory testing, not for screening. Such tests are terrible for screening. So this might be able to insert itself between the screening test (e.g. mammo, psa, or CXR) and the biopsy, but it won't replace the biopsy because you still have to characterize the cancer for further treatment decisions. From a mar…

If the mam (or other image) is positive for cancer, this test wont stop them doing a biopsy.

Re: New blood test could detect more than 20 types of cancer

#32

Post by jessriedel »

killjoywashere wrote: post #27
sandworm101 wrote: post #10

Earlier quoted context omitted.

It seems to have a great false positive rate, but a not-good false negative rate. It misses the bulk of stage one cancers. So its utility for early diagnosis (the important bit) is marginal at this time.

For those not in the lab business: a low false positive rate and a high false negative rate are useful for confirmatory testing, not for screening. Such tests are terrible for screening. So this might be able to insert itself between the screening test (e.g. mammo, psa, or CXR) and the biopsy, but it won't replace the biopsy because you still have to characterize the cancer for further treatment decisions. From a mar…

> For those not in the lab business: a low false positive rate and a high false negative rate are useful for confirmatory testing, not for screening. Such tests are terrible for screening.

Newbie question: wouldn't a test with very few false positives, but frequent false negatives, still be good for screening if it was cheaper/easier than existing screening, so it could be given to more of the population based on a weaker suspicion threshold? Like, in the limit of it being free and having zero false-positive rate, you'd give it to everyone.

(Maybe given your expertise it's obvious to you that the test is sufficiently expensive that this argument doesn't apply?)

Re: New blood test could detect more than 20 types of cancer

#33

Post by kaikai »

A pathologist friend told me “there’s a good chance you already have the cancer that might eventually kill you.” The danger of early detection of cancer is that we’ll end up treating fat more people than we would otherwise, and cancer treatment is often brutal. I’ll be interested to see what better detection actually does for mortality rates.

Re: New blood test could detect more than 20 types of cancer

#34

Post by killjoywashere »

sandworm101 wrote: post #31
killjoywashere wrote: post #27

Earlier quoted context omitted.

For those not in the lab business: a low false positive rate and a high false negative rate are useful for confirmatory testing, not for screening. Such tests are terrible for screening. So this might be able to insert itself between the screening test (e.g. mammo, psa, or CXR) and the biopsy, but it won't replace the biopsy because you still have to characterize the cancer for further treatment decisions. From a mar…

If the mam (or other image) is positive for cancer, this test wont stop them doing a biopsy.

exactly, which begs the question of why would a payer pay this?

Re: New blood test could detect more than 20 types of cancer

#35

Post by ac29 »

jessriedel wrote: post #32
killjoywashere wrote: post #27

Earlier quoted context omitted.

For those not in the lab business: a low false positive rate and a high false negative rate are useful for confirmatory testing, not for screening. Such tests are terrible for screening. So this might be able to insert itself between the screening test (e.g. mammo, psa, or CXR) and the biopsy, but it won't replace the biopsy because you still have to characterize the cancer for further treatment decisions. From a mar…

> For those not in the lab business: a low false positive rate and a high false negative rate are useful for confirmatory testing, not for screening. Such tests are terrible for screening. Newbie question: wouldn't a test with very few false positives, but frequent false negatives, still be good for screening if it was cheaper/easier than existing screening, so it could be given to more of the population based on a w…

Frequent false negatives mean it will miss many people who do have the disease, leading them to believe they are healthy until the disease progresses to a point it may be more difficult to treat.

Re: New blood test could detect more than 20 types of cancer

#36

Post by killjoywashere »

jessriedel wrote: post #32
killjoywashere wrote: post #27

Earlier quoted context omitted.

For those not in the lab business: a low false positive rate and a high false negative rate are useful for confirmatory testing, not for screening. Such tests are terrible for screening. So this might be able to insert itself between the screening test (e.g. mammo, psa, or CXR) and the biopsy, but it won't replace the biopsy because you still have to characterize the cancer for further treatment decisions. From a mar…

> For those not in the lab business: a low false positive rate and a high false negative rate are useful for confirmatory testing, not for screening. Such tests are terrible for screening. Newbie question: wouldn't a test with very few false positives, but frequent false negatives, still be good for screening if it was cheaper/easier than existing screening, so it could be given to more of the population based on a w…

If you're kicking people with cancer out of the medical system on a screening test, you're going to have a bad day.

Re: New blood test could detect more than 20 types of cancer

#37

Post by cwkoss »

cheschire wrote: post #22

One day I hope that I will have a device that can digitize my blood sample at home so that remote cloud processing can warn me of issues. Life can sometimes get in the way of preventative checks. Social anxiety might be a part of that too.

I was thinking about it in terms of cataloguing the foods you eat for later analysis, but could work for this too.

Would it be possible to make portable device that could freeze dry a drop of liquid? Heat pumps and pressure vessels both get much simpler with smaller sizes.

Re: New blood test could detect more than 20 types of cancer

#38

Post by snagglegaggle »

sandworm101 wrote: post #30
snagglegaggle wrote: post #26

Earlier quoted context omitted.

But if the tests are cheap enough you can repeat them and compare. Bringing cost of blood diagnostics down is I think a good idea. I have fitness and health conscious friends who regularly get direct-to-consumer tests as a matter of course. In a few cases they have caught issues very early. This is understanding there are some false positives, but being able to recognize them and learn to ignore them is better than n…

Repeating a test doesnt help. The blood result likely wont be different the second time. A false negative is a person for whome the test just doesnt work, no matter how many times you repeat it. (In reality, these sorts of important tests are run multiple times against the single sample before they print the results.)

For a simple false negative it would. That is a special false negative, at least to me. Is that occurrence common, and do you have an example?

Re: New blood test could detect more than 20 types of cancer

#39

Post by tyingq »

ethhics wrote: post #9

From [0], the types of cancer they can screen make up at least 81.4% of new cancer diagnoses, which means that with their 99.4% true positive rate, this test should be able to correctly identify ~80% of new cancer incidences. If I'm doing my math right, that's really impressive. [0]: https://www.wcrf.org/dietandcancer/cancer-trends/worldwide-c...

It also identifies cancers where early detection usually makes a life and death difference. Like esophageal and pancreatic and probably others.
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