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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?

#21

Post by sxg »

majorchord wrote: post #10
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…

> You're finding something that never would have caused you any problem in your life Is it though? Isn't it possible you could be early-detecting something serious that is much easier to treat now vs when symptoms appear?

Yes, you could early-detect something, but the likelihood of this thing being life-threatening are extremely low. If you choose to manage this thing aggressively anyway, you have to undergo more invasive testing (e.g., biopsies, surgery, anesthesia, etc.) that all have small risks of catastrophic events. In most cases, the risks of more invasive testing outweigh the risks of just not pursuing any further workup.

Nothing in medicine comes for free—everything is a tradeoff.

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

#22

Post by cyberax »

p0pularopinion wrote: post #18
jmward01 wrote: post #11

Maybe the right answer isn't to do a biopsy, but to monitor the area with follow-up scans? It seems like that addresses much of the harm that a false positive can cause (invasive biopsy leading to complications) while maintaining most of the gains (still very early detection).

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 like we treat blood tests.

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

#23

Post by mcbain »

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…

Spot on. And dealing with false positives sucks.

One caveat is that regular PET isn't so good in the brain - there is so much metabolic activity that everything glows. So I get an MRI Brain to go with my regular full body PET/CT (cancer 5 years ago with recurrence 18 months later, currently NED).

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

#24

Post by mcbain »

p0pularopinion wrote: post #17
rembal wrote: post #15

Earlier quoted context omitted.

Anecdotal evidence to confirm: I had two false alarms from an unrelated MRI scan, and beside wasting a lot of time on diagnosing them - it was also extremely stressful. My father is a part of "full body PET scan every 3 years" program as part of post - cancer treatment, and it worked twice: early detected lung and prostate tumors, both removed.

> My father is a part of "full body PET scan every 3 years" program as part of post - cancer treatment, These treatments are wonderful and it is great that they exist. But many people fail to understand the difference in terms of pretest probability, etc. I can absolutely see the heavy psychological impact pending biopsy results may have. People are quick to discount these issues when you raise them as a concern, but…

I have multiple scans a year. "Scanxiety" is real.

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

#25

Post by mgraczyk »

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…

And yes getting frequent full body MRIs is still overwhelming the right thing for the patient.

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

#26

Post by tptacek »

mgraczyk wrote: post #25
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…

And yes getting frequent full body MRIs is still overwhelming the right thing for the patient.

No? The point of the article, and of the preceding comments, echoing a pretty common tenet of evidence-based medicine, is that frequent full-body MRIs are a bad idea for the patient.

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

#27

Post by sharkweek »

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…

I had a CT scan last year for some stomach issues they wanted to look at.

Doctor warned me up front that the odds the images find something that looks weird is high but not to panic because of how many false positives there are when looking inside someone’s body.

While I am happy to report they didn’t find anything serious, I do take slight offense to the following at the top of my results:

Last name, First name: Unremarkable

(Kidding of course but still got a chuckle out of me)

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

#28

Post by tptacek »

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?

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

#29

Post by mgraczyk »

Doctors here are cognitively captured by a system designed to limit cost (and that's mostly a good thing)

But scanning frequently is overwhelmingly good for the patient. The problem is the doctors. Imagine two possibilities. 1. You scan every six months and a doctor reviews your scans but never tells you anything no matter what 2. You scan every six months and a doctor reviews your scans and only tells you results if you have an obviously growing mass that has a probability greater than 95% of being cancerous

Obviously #2 is better for the patient than #1, but #1 is equivalent to never testing if you ignore cost.

So the actual reason we don't have effect frequent scans combined with effective diagnostic techniques is cost, and doctors cope with this reality by saying clearly wrong things about "over diagnosis". It's a local minimum of the payer/provider dynamic that has nothing to do with scans per se.

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

#30

Post by [deleted] »

tptacek wrote: post #26
mgraczyk wrote: post #25

Earlier quoted context omitted.

And yes getting frequent full body MRIs is still overwhelming the right thing for the patient.

No? The point of the article, and of the preceding comments, echoing a pretty common tenet of evidence-based medicine, is that frequent full-body MRIs are a bad idea for the patient.

[deleted]
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