5 ms·

Eventually, this is all about cost. cfDNA assays are targetted to in the end cost less than 100 bucks per sample which for the detection of a single cancer puts

by patall 6y ago

Eventually, this is all about cost. cfDNA assays are targetted to in the end cost less than 100 bucks per sample which for the detection of a single cancer puts you in the range of $12000 for one tumor diagnosis. Ideally, you can now decrease the therapy cost of that one diagnosis while also boosting survival chances. And $12000 is not much in tumor therapy. The key however here is the advanced prognosis that may allow totally different therapeutic approaches, extend the understanding risk factors etc. and the fact that you do not need to have a specialist on side, taking a blood sample can in principle be done at home and the rest is automatic. Edit: Oh, and 5% false positives is not that bad actually, I do not have numbers is my head but would expect other essays like breast cancer screening to be also in that range.

helsinkiandrew 6y ago
5% false positives on people who have some symptoms of cancer isn’t bad. But 5% of a ‘high risk group’ could be a lot - particularly if the cancer is too early to confirm detection any other way yet and possibly not treatable for several years.
- minerjoe 6y ago
  They'll find something to sell in this case.
  - ethbro 6y ago
    Time provides options in cancer. Even if the first option is "get more regular checkups over the next year+, to characterize the growth rate." You don't have to nuke an organ from orbit, if you have historical data that indicates a tumor isn't aggressive. Or you would, if you've been watching it and it suddenly takes off.
    - minerjoe 6y ago
      "You don't" but many doctors sure seem happy to treat early and to be blind to the potential harm that the treatement entails.
      - ethbro 6y ago
        And many software developers don't properly use a CVS. But that doesn't make GitHub a bad idea.
        batty_alex 6y ago
        The problem is that you don’t want to treat every cancer like it’s potentially life-threatening (many aren’t) because you can cause other problems with detection/treatment. I’d want any early detection to be pretty damn solid if we’re going to start talking monthly checkups for something that could resolve on its own. Using an SCM tool isn’t going to cause additional problems except for reminding yourself of all the dumb mistakes you made last week.
        ethbro 6y ago
        > Using an SCM tool isn’t going to cause additional problems except for reminding yourself of all the dumb mistakes you made last week. You haven't worked at a shop that mandated Team Foundation Server, have you? ;)
- refurb 6y ago
  But in this example - stomach cancer - you could just skip the test and do a routine endoscopy and get some tissue samples. You’d have a much higher confidence in the result. Reminds me a bit of the PSA test for prostate cancer. More of an early warning, but with the weak predictability, doctors are moving away from routine PSA tests.
  - jjk166 6y ago
    If option A is regular blood tests with an endoscopy to confirm should the blood test come back positive and option B is getting endoscopies on a regular basis, option A is a no brainer. While it might not be super invasive, I'd definitely like to keep the number of times a tube has to be shoved down my throat to a minimum.
    - refurb 6y ago
      But if the false positive rate is high, just skip the test and do the endoscopy.
      - jjk166 6y ago
        No, the false positive rate is irrelevant. Let's say you want to check for cancer annually and the blood test has a 50% false positive rate: If you only get endoscopies after positive results, you get an endoscopy every other year. If you skip the test and go straight to the endoscopy, you get one every year. Thus you get half as many tubes shoved down your throat if you get the blood test. For a more reasonable false positive rate like 5%, you would have a 50/50 chance of getting a false positive any given decade. I'd much rather get 4 endoscopies than 40. Indeed, for any false positive rate less than 100% (which isn't really a test to begin with) still on average decreases the number of endoscopies you need. Really the metric that's important is the false negatives: if that's too high then I can't safely forego the endoscopy just because this year's blood test was negative. Even then though, if the blood test has a long lead time then maybe it's safe to wait and see how next year's blood test goes.
488643689 6y ago
The problem is with breast cancer screening the next step probably isn't a full body CT. If you detect cancer in the blood, next step would be actually finding it. A full body CT would actually increase your cancer risk and add the chances for another false positive which might involve more invasive diagnosis. The real risk/benefit calculations quickly become tricky. All that said, I'd rather risk dying while propofol'ed, than from say colon cancer. I mean all this is about how we die, not if we have to die.
- fqwefqwef902 6y ago
  Coming from the field of cognitive neuroscience, where MRI scans are commonplace (because you can get an estimate of brain activity by doing a continuous, "functional" MRI scan), CT feels like ancient technology to me. There are highly specific case where it has benefits, so it has a place. But if I went into the hospital and they sent me in for CT rather than MRI to get an anatomical scan, they better have a damn good reason for it.
  - carbocation 6y ago
    CT and MRI are simply different imaging modalities that provide different information, usually used to answer different questions. There are tradeoffs for each. By the way, they were both invented around the same time (CT is only older by like ~5 years).
  - hylaride 6y ago
    Excuse my ignorance, but I've always been told that CTs are significantly cheaper and faster to administer. According to the famous XKCD radiation graph, a full CT head scan is about 50% of the normal natural yearly background radiation you'll get. Not something to cheer over, but nothing to lose sleep over either. If a CT scan would suffice, why tie up the MRI machine?
    - hda111 6y ago
      The dosage is in a shorter amount of time (within seconds instead of months). I don’t think the radiation averaged over half a year is comparable to the head CT.
HeadsUpHigh 6y ago
If you need 12k$ for a single tumor diagnosis, then we should consider MRI imaging. Those cost significantly less than that. And as of right now, the positive effects of chemotherapy on such early cancers would be debatable. Still a useful development though.
- 488643689 6y ago
  Worth noting an MRT is of low value for prevention. Small lesions would be invisible and you could very well progress from nothing visible to seriously sick in 6 month. We really need some marker for before we get unhindered growth. Even if we had 100% precise AI assisted image analysis, once a year fullbody MRI... the MRI resolution would still not catch the "before things escalate quickly" pre stage of cancer. With imagery catching _most cancers early is inherently a thing of mostly luck.
- patall 6y ago
  You misunderstand. 12k$ (or some number in that ballpark) would be per postive test for testing everyone. Your 12k$ for MRI would check a single person. That's something totally different. The point is that treating a cancer patient easily costs tens or of hundreds of thousands plus dire consequences for the patient themselves. So there is a lot of room for improvement if the diagnosis is made that much earlier.
noknownsender 6y ago
Another potential benefit of this sort of early detection would be the ability to more effectively test interventions that might have little effect on more advanced cancers. That could help direct research into the development of cancers at its earliest stages, and potentially pave the way for more effective prevention.

by patall 6y ago

helsinkiandrew 6y ago

5% false positives on people who have some symptoms of cancer isn’t bad. But 5% of a ‘high risk group’ could be a lot - particularly if the cancer is too early to confirm detection any other way yet and possibly not treatable for several years.

minerjoe 6y ago
They'll find something to sell in this case.
- ethbro 6y ago
  Time provides options in cancer. Even if the first option is "get more regular checkups over the next year+, to characterize the growth rate." You don't have to nuke an organ from orbit, if you have historical data that indicates a tumor isn't aggressive. Or you would, if you've been watching it and it suddenly takes off.
  - minerjoe 6y ago
    "You don't" but many doctors sure seem happy to treat early and to be blind to the potential harm that the treatement entails.
    - ethbro 6y ago
      And many software developers don't properly use a CVS. But that doesn't make GitHub a bad idea.
      - batty_alex 6y ago
        The problem is that you don’t want to treat every cancer like it’s potentially life-threatening (many aren’t) because you can cause other problems with detection/treatment. I’d want any early detection to be pretty damn solid if we’re going to start talking monthly checkups for something that could resolve on its own. Using an SCM tool isn’t going to cause additional problems except for reminding yourself of all the dumb mistakes you made last week.
        ethbro 6y ago
        > Using an SCM tool isn’t going to cause additional problems except for reminding yourself of all the dumb mistakes you made last week. You haven't worked at a shop that mandated Team Foundation Server, have you? ;)
refurb 6y ago
But in this example - stomach cancer - you could just skip the test and do a routine endoscopy and get some tissue samples. You’d have a much higher confidence in the result. Reminds me a bit of the PSA test for prostate cancer. More of an early warning, but with the weak predictability, doctors are moving away from routine PSA tests.
- jjk166 6y ago
  If option A is regular blood tests with an endoscopy to confirm should the blood test come back positive and option B is getting endoscopies on a regular basis, option A is a no brainer. While it might not be super invasive, I'd definitely like to keep the number of times a tube has to be shoved down my throat to a minimum.
  - refurb 6y ago
    But if the false positive rate is high, just skip the test and do the endoscopy.
    - jjk166 6y ago
      No, the false positive rate is irrelevant. Let's say you want to check for cancer annually and the blood test has a 50% false positive rate: If you only get endoscopies after positive results, you get an endoscopy every other year. If you skip the test and go straight to the endoscopy, you get one every year. Thus you get half as many tubes shoved down your throat if you get the blood test. For a more reasonable false positive rate like 5%, you would have a 50/50 chance of getting a false positive any given decade. I'd much rather get 4 endoscopies than 40. Indeed, for any false positive rate less than 100% (which isn't really a test to begin with) still on average decreases the number of endoscopies you need. Really the metric that's important is the false negatives: if that's too high then I can't safely forego the endoscopy just because this year's blood test was negative. Even then though, if the blood test has a long lead time then maybe it's safe to wait and see how next year's blood test goes.

488643689 6y ago

The problem is with breast cancer screening the next step probably isn't a full body CT. If you detect cancer in the blood, next step would be actually finding it. A full body CT would actually increase your cancer risk and add the chances for another false positive which might involve more invasive diagnosis. The real risk/benefit calculations quickly become tricky. All that said, I'd rather risk dying while propofol'ed, than from say colon cancer. I mean all this is about how we die, not if we have to die.

fqwefqwef902 6y ago
Coming from the field of cognitive neuroscience, where MRI scans are commonplace (because you can get an estimate of brain activity by doing a continuous, "functional" MRI scan), CT feels like ancient technology to me. There are highly specific case where it has benefits, so it has a place. But if I went into the hospital and they sent me in for CT rather than MRI to get an anatomical scan, they better have a damn good reason for it.
- carbocation 6y ago
  CT and MRI are simply different imaging modalities that provide different information, usually used to answer different questions. There are tradeoffs for each. By the way, they were both invented around the same time (CT is only older by like ~5 years).
- hylaride 6y ago
  Excuse my ignorance, but I've always been told that CTs are significantly cheaper and faster to administer. According to the famous XKCD radiation graph, a full CT head scan is about 50% of the normal natural yearly background radiation you'll get. Not something to cheer over, but nothing to lose sleep over either. If a CT scan would suffice, why tie up the MRI machine?
  - hda111 6y ago
    The dosage is in a shorter amount of time (within seconds instead of months). I don’t think the radiation averaged over half a year is comparable to the head CT.

HeadsUpHigh 6y ago

If you need 12k$ for a single tumor diagnosis, then we should consider MRI imaging. Those cost significantly less than that. And as of right now, the positive effects of chemotherapy on such early cancers would be debatable. Still a useful development though.

488643689 6y ago
Worth noting an MRT is of low value for prevention. Small lesions would be invisible and you could very well progress from nothing visible to seriously sick in 6 month. We really need some marker for before we get unhindered growth. Even if we had 100% precise AI assisted image analysis, once a year fullbody MRI... the MRI resolution would still not catch the "before things escalate quickly" pre stage of cancer. With imagery catching _most cancers early is inherently a thing of mostly luck.
patall 6y ago
You misunderstand. 12k$ (or some number in that ballpark) would be per postive test for testing everyone. Your 12k$ for MRI would check a single person. That's something totally different. The point is that treating a cancer patient easily costs tens or of hundreds of thousands plus dire consequences for the patient themselves. So there is a lot of room for improvement if the diagnosis is made that much earlier.

noknownsender 6y ago

Another potential benefit of this sort of early detection would be the ability to more effectively test interventions that might have little effect on more advanced cancers. That could help direct research into the development of cancers at its earliest stages, and potentially pave the way for more effective prevention.