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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?

#181

Post by blincoln »

bell-cot wrote: post #176
rustyhancock wrote: post #53

Earlier quoted context omitted.

It's not that MRIs suck at cancer. They provide fantastic structural and functional data. The problem is the specificity of the results and the prior. A full body MRI by definition will provide detailed views of areas where the pretest probability for cancer is negligible. That means even a specific test would result in a high risk of false positives. As a counter point, MRS means that you can now MRI someone's prost…

> Lets say someone has lower urinary tract symptoms. And is 60 years old. An MRI could visualize as well as ... Not a doctor - but maybe start with some quick & cheap tests of their blood & urine, polite questions about their sexual partners, and possibly an ultrasound peek at things? At least in America, high-tech scans are treated as a cash cow. And cheap & reasonable tests, if done, are merely an afterthought - af…

> At least in America, high-tech scans are treated as a cash cow. And cheap & reasonable tests, if done, are merely an afterthought - after the patient has been milked for all the scan-bucks that their insurance will pay out.

Maybe it's a regional thing, but that hasn't been my experience. I've had one MRI and one CT scan in the 25+ years that I've been a full-time employed adult with insurance.

I'd have been happy to sign up for more so I could have proactive health information and the raw data to use for hobby projects.

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

#182

Post by the_monocle »

Extremely anecdotal: my dad’s lung cancer was found incidentally - shoulder pain → shoulder MRI → radiologist noticed lung nodules. The shoulder pain was unrelated, but the scan itself was clinically indicated and there were prior scans to compare against, which made it immediately suspicious and triggered follow-up imaging.

He was also in a higher-risk group (age + history), which in hindsight probably made the incidental finding meaningful rather than noise.

So cases like his make me think less “scan everyone periodically” and more “imaging can be very valuable once risk is non-trivial or there’s a baseline to compare to”. For the general population you’d mostly generate false positives, but for higher-risk groups (older, smokers, prior findings) it seems much more defensible.

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

#184

Post by OneDeuxTriSeiGo »

gjulianm wrote: post #169
nayroclade wrote: post #129

Arguments against proactive MRI scanning always seem to have a whiff of status quo bias to them. Yes, right now MRIs are expensive and false positives are common, but if regular scans were widespread, it's likely this result in innovations that would drive down costs, improve accuracy, as well as producing a much larger corpus of data with which to guide diagnosis and reduce false positives. To use a software analogy…

> it's likely this result in innovations that would drive down costs, improve accuracy, as well as producing a much larger corpus of data with which to guide diagnosis and reduce false positives. Why is it likely? We already have a lot of MRI data. There are already a lot of incidental findings. It might also be an issue of the MRI not being able to produce enough information to discriminate. > To use a software anal…

> Why is it likely? We already have a lot of MRI data. There are already a lot of incidental findings. It might also be an issue of the MRI not being able to produce enough information to discriminate.

This is the main reason. Well technically the opposite of the main reason but more or less it's the same. MRIs are extremely high fidelity nowadays and as a result it's really really hard to read an MRI. Every person is different and there's a lot of variations and weird quirks. You get all the data rather than clearly identified problem areas like you get with say a CT w/ contrast, etc.

That's actually exactly why it's important to have MRIs more frequently to be able to establish baselines and identify trends as they develop.

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

#185

Post by pfdietz »

miduil wrote: post #147
nayroclade wrote: post #129

Arguments against proactive MRI scanning always seem to have a whiff of status quo bias to them. Yes, right now MRIs are expensive and false positives are common, but if regular scans were widespread, it's likely this result in innovations that would drive down costs, improve accuracy, as well as producing a much larger corpus of data with which to guide diagnosis and reduce false positives. To use a software analogy…

> Arguments against proactive MRI scanning always seem to have a whiff of status quo bias to them More and more European countries are currently adopting Lung Cancer screening programs. It's usually limited to people with a certain amount of cigarette-pack-years, but still gives the opportunity for driving more of the innovation you're talking about. I think the main challenge at the moment is that nothing in healthc…

It's helpful in justifying screening that non-small cell lung cancer treatments have greatly improved in recent years.

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

#186

Post by gcanyon »

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…

Not because of an MRI, but this happened to me:

   1. I had a chest x-ray
   2. It showed a small dark patch, and my lungs over-inflate.
   3. Erring on the side of caution, doctor ordered a lung biopsy.
   4. Lung biopsy is painful, annoying, expensive, and non-zero-risk.
   5. Lung biopsy turns up nothing. "Maybe you aspirated some food?" We learn nothing.
N=1, but that biopsy should not have happened.

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

#187

Post by preommr »

srean wrote: post #136
nayroclade wrote: post #129

Arguments against proactive MRI scanning always seem to have a whiff of status quo bias to them. Yes, right now MRIs are expensive and false positives are common, but if regular scans were widespread, it's likely this result in innovations that would drive down costs, improve accuracy, as well as producing a much larger corpus of data with which to guide diagnosis and reduce false positives. To use a software analogy…

False positives trigger more diagnostics some of which can be harmful, not just psychologically but physiologically as well. If false positives are ok, why not build a down time detector that rolls a die every 5 mins and alert on hitting a 6.

> some of which can be harmful,

Like what?

I've seen instances where this is used as an excuse for what is, ostensibly, a trick to dimiss people using something that sounds vaguely professional. Like when doctors say they don't want to do additional x-rays because of the risk of radiation exposure, nvm that if it comes out slightly blurry they'll ask to redo it, or if you're cautious about it initially they'll tell you how it's not big deal and there's more radiation in a cluster of bananas.

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

#188

Post by doRadiology »

the_monocle wrote: post #182

Extremely anecdotal: my dad’s lung cancer was found incidentally - shoulder pain → shoulder MRI → radiologist noticed lung nodules. The shoulder pain was unrelated, but the scan itself was clinically indicated and there were prior scans to compare against, which made it immediately suspicious and triggered follow-up imaging. He was also in a higher-risk group (age + history), which in hindsight probably made the inci…

Sorry to hear about your dad.

Wrt the issue at hand: yes the cancer was found as an incidental finding on a scan performed for another indication (shoulder pain) -> the question remains whether your father benefitted from finding the cancer. This is seldomly the case.

Anecdotally, everything is possible but on a population scale, actual survival benefit is rare - whereas suffering from the downsides is not - even if only counting unnecessary healthcare cost and time wasted.

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

#189

Post by ryan_n »

gcanyon wrote: post #186
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…

Not because of an MRI, but this happened to me: 1. I had a chest x-ray 2. It showed a small dark patch, and my lungs over-inflate. 3. Erring on the side of caution, doctor ordered a lung biopsy. 4. Lung biopsy is painful, annoying, expensive, and non-zero-risk. 5. Lung biopsy turns up nothing. "Maybe you aspirated some food?" We learn nothing. N=1, but that biopsy should not have happened.

I don’t understand how you’re concluding that the biopsy shouldn’t have happened from that anecdote? Just because a test result is negative doesn’t mean that it shouldn’t have happened. That’s not how practicing medicine works.

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

#190

Post by terminalshort »

gjulianm wrote: post #169
nayroclade wrote: post #129

Arguments against proactive MRI scanning always seem to have a whiff of status quo bias to them. Yes, right now MRIs are expensive and false positives are common, but if regular scans were widespread, it's likely this result in innovations that would drive down costs, improve accuracy, as well as producing a much larger corpus of data with which to guide diagnosis and reduce false positives. To use a software analogy…

> it's likely this result in innovations that would drive down costs, improve accuracy, as well as producing a much larger corpus of data with which to guide diagnosis and reduce false positives. Why is it likely? We already have a lot of MRI data. There are already a lot of incidental findings. It might also be an issue of the MRI not being able to produce enough information to discriminate. > To use a software anal…

We do not have a lot of MRI data. The average person probably gets a couple MRIs in their lifetime, and this is biased because we wait until something is clearly wrong to get the MRI. If you want to find an MRI scan of an early stage asymptomatic cancer, the only data on that will be the exceedingly rare case that someone has something else unrelated wrong with them in the same general area and gets an MRI for that, and then just by chance also has the early stage cancer at the same time.
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