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How often do full-body MRIs find cancer?

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Re: How often do full-body MRIs find cancer?

#31

Post by tptacek »

cyberax wrote: post #22
p0pularopinion wrote: post #18

Earlier quoted context omitted.

The problem is that just because you‘re detecting something, it does not mean it is worth watching. Bodies are not standardized and most people habe something off. But you can‘t really reschedule everybody constantly, as that would entirely break the concept.

"Worth watching" implies that watching is expensive. It's really not. A full-body MRI scan is about $1k, and it can be even cheaper. So if you have abnormal findings in 10% of patients that merit follow-up scans, you can trivially do a series of 3-4 scans without affecting the overall cost too much. Doctors simply need to get out of the headspace where MRIs are extremely scarce tools of last resort and treat them lik…

I think you're missing the point. The psychological cost of a conditional-positive result is nonzero, and can be very significant (I speak from a little bit of experience here). But far more importantly: the physiological cost of invasive followups when you eventually trip the threshold of "time to go explore with a scalpel" is very high, and the missing evidence this story is about is whether you can get to that threshold with an MRI.

Treating MRIs the way we treat blood tests would almost certainly result in huge numbers of needless invasive procedures.

Re: How often do full-body MRIs find cancer?

#32

Post by paulpauper »

mmaunder wrote: post #13

“ One study in 2020 found that 95% of asymptomatic patients had some type of "abnormal" finding, but just 1.8% of these findings were indeed cancer.” This has been my experience. And I’ve had oncologists echo exactly this. In the words of one: MRIs find too much. The CT and the PET/CT are the gold standards for finding cancer, finding recurrences, and staging cancer. The trouble is the radiation dose. MRI provides ve…

hmm that is still around 1.5% of ppl having cancer. not trivial. Even more if you include false negatives.

Re: How often do full-body MRIs find cancer?

#33

Post by paulpauper »

lucb1e wrote: post #2

Answering the question in the title... > One study in 2020 found that 95% of asymptomatic patients had some type of "abnormal" finding, but just 1.8% of these findings were indeed cancer. So a bit less than 1.8% of the time in this study > Prenuvo's recent Polaris Study followed 1,011 patients for at least one year following a whole-body MRI scan. Of these patients, 41 had biopsies. More than half of the 41 were diag…

Yeah a 2% risk of having something which can easily kill you and is very expensive to treat, especially if you're not elderly and still have lots of life ahead of your, is not exactly trivial. I would want to know about this

Re: How often do full-body MRIs find cancer?

#34

Post by giantg2 »

tptacek wrote: post #28
giantg2 wrote: post #20

Just to point out, cancer isn't the only reason to get these. Aneurisms, hemachromatosis, etc can all be serious. I know someone who got scanned for $500 and they caught hemachromatosis via iron deposits in the liver. Much better than eventual chirrosis and liver failure.

What's the base rate of hemachromatosis in the population and what's the false positive rate for MRI detection of the condition?

MRI does not diagnose hemachromatosis. It detects iron deposits (could be due to other harmful issues). To my knowledge it would not produce a false positive. Hemachromatosis is the most common genetic issue in white people, so pretty common (I'm too lazy to look up stats).

Re: How often do full-body MRIs find cancer?

#35

Post by jamesbelchamber »

One important point is that many people die WITH cancer but not OF cancer. So even for the 1.8%, only a fraction of those people were going to die of the disease (or even suffer significant symptoms) - the rest were just going to die of natural causes anyway.

But now you've found it you pretty much have to remove it, which has significant quality of life implications.

Re: How often do full-body MRIs find cancer?

#37

Post by jmward01 »

cyberax wrote: post #22
p0pularopinion wrote: post #18

Earlier quoted context omitted.

The problem is that just because you‘re detecting something, it does not mean it is worth watching. Bodies are not standardized and most people habe something off. But you can‘t really reschedule everybody constantly, as that would entirely break the concept.

"Worth watching" implies that watching is expensive. It's really not. A full-body MRI scan is about $1k, and it can be even cheaper. So if you have abnormal findings in 10% of patients that merit follow-up scans, you can trivially do a series of 3-4 scans without affecting the overall cost too much. Doctors simply need to get out of the headspace where MRIs are extremely scarce tools of last resort and treat them lik…

I totally agree. US healthcare is broken and costs aren't tied to the reality of how expensive something actually is. I have very high hopes that modern medicine is in for a massive disruptive change where things like full body MRI, along with analysis, could be done very cheap and with no admin overhead. In that model 'we see something we aren't sure of. It is probably nothing but to be sure we want to do follow-ups' is far less of a problem.

A lot of this however is how it is discussed with the patient. Discussions about the likelihood of there being a real issue when something is seen need to be clear and informative without being alarming. 'We did a routine scan and these often show transient artifacts that turn out to be nothing, but in an abundance of caution we want to do a followup' is totally different than 'we saw something we are concerned about and need to do a followup'. How things are messaged really matters.

Re: How often do full-body MRIs find cancer?

#38

Post by cogman10 »

jamesbelchamber wrote: post #35

One important point is that many people die WITH cancer but not OF cancer. So even for the 1.8%, only a fraction of those people were going to die of the disease (or even suffer significant symptoms) - the rest were just going to die of natural causes anyway. But now you've found it you pretty much have to remove it, which has significant quality of life implications.

This seems like a wild statement.

Age is a big factor in the with/of cancer factor. If someone is 80 years old then there's good chance it won't be cancer that kills them (assuming they aren't already in a late stage).

But if you are 40 and you have cancer, there's a good chance you'll die of that cancer if it's left untreated.

I'm personally of the opinion that cancer screening should happen earlier for younger people and less frequently for older people. Like, if you hit 80, there's really basically no reason to screen for cancer.

Re: How often do full-body MRIs find cancer?

#39

Post by NedF »

mmaunder wrote: post #13

“ One study in 2020 found that 95% of asymptomatic patients had some type of "abnormal" finding, but just 1.8% of these findings were indeed cancer.” This has been my experience. And I’ve had oncologists echo exactly this. In the words of one: MRIs find too much. The CT and the PET/CT are the gold standards for finding cancer, finding recurrences, and staging cancer. The trouble is the radiation dose. MRI provides ve…

[dead]

Re: How often do full-body MRIs find cancer?

#40

Post by bawolff »

paulpauper wrote: post #32
mmaunder wrote: post #13

“ One study in 2020 found that 95% of asymptomatic patients had some type of "abnormal" finding, but just 1.8% of these findings were indeed cancer.” This has been my experience. And I’ve had oncologists echo exactly this. In the words of one: MRIs find too much. The CT and the PET/CT are the gold standards for finding cancer, finding recurrences, and staging cancer. The trouble is the radiation dose. MRI provides ve…

hmm that is still around 1.5% of ppl having cancer. not trivial. Even more if you include false negatives.

I mean, i think you need to look more into it than that.

If you make a test that always returns true, it would also meet that criteria.

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