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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?

#191

Post by the_monocle »

doRadiology wrote: post #188
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…

In my dad’s case it very likely did - it was lung cancer and still pre-symptomatic, but had already started to metastasize, so a later discovery would probably have meant a much worse prognosis category.

I agree anecdotes don’t generalize and broad population screening sounds like a bad tradeoff. What I’m wondering about instead is risk-stratified situations: once someone already has elevated risk or prior lung disease and you’re imaging them periodically for legitimate reasons, incidental findings may carry much more signal than noise.

For example, people with prior tuberculosis often get periodic chest X-rays, not to screen the general population, but because their baseline risk is different. My dad had prior lung disease and existing imaging to compare against, which probably made the finding actionable rather than just another false positive.

So not “scan everyone”, more “the usefulness of incidental findings rises quickly once pre-test probability isn’t tiny”.

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

#192

Post by giantg2 »

lostlogin wrote: post #76
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.

A blood test is a far cheaper way to check this.

A blood test doesn't scan for other issues. A genetic test and iron study is going to run a few hundred dollars. Add in the cumulative cost for the other conditions checked for, like aneurism, and a $500 MRI isn't that bad.

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

#193

Post by giantg2 »

lostlogin wrote: post #110
mapt wrote: post #106

Earlier quoted context omitted.

No it isn't. If you get the MRI you are performing simultaneous blind tests for a thousand rare, unsuspected conditions. The blood test only tests for one of them, and eats 10ml of blood. There isn't enough blood in your body for all those tests. We should arguably be, in an ideal healthcare system, getting annual MRIs with the other typical tests in a physical, and feeding that data into an AI, and have the AI issue…

> The blood test only tests for one of them, and eats 10ml of blood. There isn't enough blood in your body for all those tests. There is some irony here. Getting some blood out is what will cure that iron overload.

"There is some irony here. Getting some blood out is what will cure that iron overload."

The real irony here is that you think treating an undiagnosed condition is a bonus. The patient could just as likely be suffering from anemia...

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

#194

Post by randallsquared »

preommr wrote: post #187
srean wrote: post #136

Earlier quoted context omitted.

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 y…

> Like what?

Well, from the original article: "And if someone is over-diagnosed, gets a biopsy and develops an infection, that's a direct harm."

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

#195

Post by patja »

preommr wrote: post #187
srean wrote: post #136

Earlier quoted context omitted.

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 y…

A colonoscopy has the risk of going very wrong due to a puncture.

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

#196

Post by n8henrie »

kcexn wrote: post #135
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…

There's a softer component to healthcare which is that people can overreact to medical results. If a doctor administers a scan, finds a handful of likely benign things but wants to administer another scan later on down the line, I'm probably much more likely to look for a second opinion that tells me to cut them out (even if it may not be medically necessary) than trust my doctor that "it's probably fine". It's proba…

Not to mention the malpractice risk and potential for extra income, which -- depending on where you live -- may strongly (if subconsciously) influence your physicians interpretations and recommendations.

Do you think a doctor is more likely to call something "possible cancer" and recommend that you either have a specialist do a biopsy (keeping in mind that many of these will be... hard to reach) or at least have a follow up MRI in 3, 6, 9 months?

Or tell you it's "pretty unlikely to be cancer, I don't think we need to worry about it" and then get sued for 20M when they are wrong about 1 in 100 cases (not to mention missing out on all the potential income from above).

At least in the US, the incentives here are grossly misaligned.

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

#197

Post by randallsquared »

blackcatsec wrote: post #148
jb1991 wrote: post #139

Earlier quoted context omitted.

Additional diagnostics can also be very expensive. Articles like this don’t seem to understand the overall costs to a health system with decisions like these. And that cost eventually does go down into the pockets of patients one way or another.

I think the point of the conversation is that if we take the predatory capitalism out of the way, using MRIs could potentially be a net benefit overall for everyone.

OECD data (most recent available, around 2020–2022): MRI units per 100K population: United States ~3.6, Canada ~1.0, United Kingdom ~0.7

I would argue that getting "predatory capitalism" out of the way has sharply curtailed MRI availability where that's been tried. Maybe we should loosen the leash on capitalism a bit to get better care...

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

#198

Post by n8henrie »

preommr wrote: post #187
srean wrote: post #136

Earlier quoted context omitted.

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 y…

Like when someone has an anaphylactic reaction to the contrast dye for their CT?

Contrast-induced nephropathy?

Gadolinium accumulation in the brain doesn't sound good for you...

Although I think this argument is usually talking about the risks of the resulting procedures (eg an injury or complication related to a biopsy done for a finding on imaging).

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

#199

Post by vharuck »

MagicMoonlight wrote: post #144
srean wrote: post #136

Earlier quoted context omitted.

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.

Harmful to shareholder value. Personally I’d rather have cancer checked out rather than have a “wait and die” approach

The United States Preventative Services Task Force[1] reviews studies and meta-studies to make recommendations about screening procedures. Their ratings are used by Medicare and Medicaid to decide what's covered and for which patients. In turn, many private insurance companies cover the same procedures. The USPSTF explicitly doesn't consider cost in their recommendations. Most often, they look at whether a screening reduces mortality rates.

1: https://www.uspreventiveservicestaskforce.org/

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

#200

Post by Bender »

JackFr wrote: post #160
MagicMoonlight wrote: post #142

Earlier quoted context omitted.

No, this is more like disabling logging because people are concerned the server is going down. “Don’t worry about it, I don’t think it’s a real issue so we’re just going to ignore it”

But if you’ve never looked at the log before all these WARNINGs might be normal operation. It’s not turning off logging, it’s saying log at ERROR level.

That's a good point. How many people have a baseline MRI from when they were at their healthiest?
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