“ 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 very inconclusive results. You’ll see something but it’ll be unclear what it is. And often what you see is not even visible on a CT. Or it’s visible on a PET/CT and is showing metabolic activity indicating its cancer.
MRIs are great for certain things like herniated disks in your back. They suck at cancer.
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).
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 only if they never went through this stress themselves
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)
MRIs are good if you know what you’re looking for, and usually with contrast, which in a situation like cancer where you need to do them often can result in allergic reactions.
In a full body situation, they are looking for mets, and the uptake of radioactive sugar by the tumors will let a PET scan find them.
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.
> 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 diagnosed with cancer.
That's 2.0%
Note that this doesn't mean that 1.7~2.0% of people have cancer without knowing it. It could be more:
> A negative scan doesn’t mean you’re disease-free. Some cancers and conditions simply aren’t visible yet or aren’t reliably detected on a one-time full-body MRI."
But also perhaps less, in a way:
> "You're finding something that never would have caused you any problem in your life, and in cancer, we call that overdiagnosis," Vickers says.
Yep, I have experience with both. It found cancer for my wife and she was able to treat it immediately. Fully recovered.
It found a weird spot on me that turned out to a pancreatic rest.
The only reason we did the scans were because we were making a significant life decision that we didn’t want to have to backtrack if either got diagnosed with cancer within a year . We knew nothing was guaranteed but we wanted to do some tests.
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.
> Isn't it possible you could be early-detecting something serious that is much easier to treat now vs when symptoms appear?
It could be. It could also be the cade that you undergo invasive surgery for something that would have never caused you problems within your life. The problem is that cancer isn‘t cancer. Even if it originates from the same tissue, some tumors behave very different from others.
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
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.
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).
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.
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.
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.
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.
I pay an extra $60 a year to have my ophthalmologist take a digital image of my retina. It comes back as normal every year, but if something does change we can diff the image against the baseline.
Maybe I don't want to look for cancer right now but if I spend $1,000 every 5 years to take an image for later use... isn't that useful?
Might be, but in the context it's also worth asking what better options you have for your health with that $1000.
(for some people that question may not apply, of course, but at a population level it does, and we have population-level questions about effective use of MRI time.). And if there's something better, you should spend it on that and then ask the question _again_. So it could be that getting a whole-body MRI is something like $30k down the list of best ways to spend money for improved health.
I'm not sure what the best use of $1k is from a health standpoint is, just noting that it's good to have a comparator.
> I'm not sure what the best use of $1k is from a health standpoint is, just noting that it's good to have a comparator.
Spending 1k on a gym membership and more fresh vegetables would be a pretty high return on investment, if one isn't in shape and eating healthy already.
Yes, and it seems like its purposefully ignored in the "body scan" debate. full CT scans would be more problematic, and MRI's (especially no contrast ones) don't pick up a lot of things... but having annual comparisons over a few years would likely fill in some of those gaps. literally and figuratively.
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.
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.
It does, doesn't it! This is basically the reason scepticism in screening has risen (amongst scientists and medics, not the general population) - research seems to show that screening catches much more cancer but doesn't save many more people.
Rohin Francis does a good video on it, which you don't have to watch because it has references underneath you can click straight through to (the video is good though): https://youtu.be/yNzQ_sLGIuA
I am frustrated by this because it seems obvious to me that "more data == better" but I guess it makes sense if you think of the scans as having high amounts of noise, and us having a poor understanding of the system we're monitoring (this never happens in tech, of course :)).
I don't see the point of testing constantly. It's just creating stress and probably most of the time, the tumor might be benign or it might be small and go away on its own.
And anyway, you have to die of something so for me cancer would just be a sign that time's up.
There’s a major difference between having insurance cover something (socialized cost, immediately drives up provider fees for bizarre reasons) and letting the market allow people to buy it themselves (individual cost, the market drives the cost down fast and hard). Notice the pattern with LASIK and GLP1 where lack of insurance coverage has counterintuitively made it cheaper and more accessible.
Let everyone who wants to pay get their scans! But don’t make me pay for you
“ 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 very inconclusive results. You’ll see something but it’ll be unclear what it is. And often what you see is not even visible on a CT. Or it’s visible on a PET/CT and is showing metabolic activity indicating its cancer.
MRIs are great for certain things like herniated disks in your back. They suck at cancer.
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).
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 only if they never went through this stress themselves
I have multiple scans a year. "Scanxiety" is real.
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)
“MRIs…suck at cancer”
Wrong? I understand MRIs are the standard for certain types of cancer like brain and spinal tumors.
With respect to whole body MRI they can be less effective because it’s not optimized, accuracy can be traded for area.
But as a general statement MRIs do not suck at cancer.
MRIs are good if you know what you’re looking for, and usually with contrast, which in a situation like cancer where you need to do them often can result in allergic reactions.
In a full body situation, they are looking for mets, and the uptake of radioactive sugar by the tumors will let a PET scan find them.
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.
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.
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 diagnosed with cancer.
That's 2.0%
Note that this doesn't mean that 1.7~2.0% of people have cancer without knowing it. It could be more:
> A negative scan doesn’t mean you’re disease-free. Some cancers and conditions simply aren’t visible yet or aren’t reliably detected on a one-time full-body MRI."
But also perhaps less, in a way:
> "You're finding something that never would have caused you any problem in your life, and in cancer, we call that overdiagnosis," Vickers says.
Yep, I have experience with both. It found cancer for my wife and she was able to treat it immediately. Fully recovered.
It found a weird spot on me that turned out to a pancreatic rest.
The only reason we did the scans were because we were making a significant life decision that we didn’t want to have to backtrack if either got diagnosed with cancer within a year . We knew nothing was guaranteed but we wanted to do some tests.
> 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.
> Isn't it possible you could be early-detecting something serious that is much easier to treat now vs when symptoms appear?
It could be. It could also be the cade that you undergo invasive surgery for something that would have never caused you problems within your life. The problem is that cancer isn‘t cancer. Even if it originates from the same tissue, some tumors behave very different from others.
>"More men die with prostate cancer than because of it" - an old adage that still holds true in the 21st century
https://pubmed.ncbi.nlm.nih.gov/33360667/
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
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).
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.
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.
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.
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.
I pay an extra $60 a year to have my ophthalmologist take a digital image of my retina. It comes back as normal every year, but if something does change we can diff the image against the baseline.
Maybe I don't want to look for cancer right now but if I spend $1,000 every 5 years to take an image for later use... isn't that useful?
Might be, but in the context it's also worth asking what better options you have for your health with that $1000.
(for some people that question may not apply, of course, but at a population level it does, and we have population-level questions about effective use of MRI time.). And if there's something better, you should spend it on that and then ask the question _again_. So it could be that getting a whole-body MRI is something like $30k down the list of best ways to spend money for improved health.
I'm not sure what the best use of $1k is from a health standpoint is, just noting that it's good to have a comparator.
> I'm not sure what the best use of $1k is from a health standpoint is, just noting that it's good to have a comparator.
Spending 1k on a gym membership and more fresh vegetables would be a pretty high return on investment, if one isn't in shape and eating healthy already.
Yes, and it seems like its purposefully ignored in the "body scan" debate. full CT scans would be more problematic, and MRI's (especially no contrast ones) don't pick up a lot of things... but having annual comparisons over a few years would likely fill in some of those gaps. literally and figuratively.
Er wait is retinal cancer a thing?
Yes. Like OP, I do a picture every year. Three years ago there was a scare, that turned out to be nothing.
Yes. You can also have melanoma on your uvea
theres a ton of degeneative stuff too that's not strongly age corrilated.
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.
It does, doesn't it! This is basically the reason scepticism in screening has risen (amongst scientists and medics, not the general population) - research seems to show that screening catches much more cancer but doesn't save many more people.
Rohin Francis does a good video on it, which you don't have to watch because it has references underneath you can click straight through to (the video is good though): https://youtu.be/yNzQ_sLGIuA
I am frustrated by this because it seems obvious to me that "more data == better" but I guess it makes sense if you think of the scans as having high amounts of noise, and us having a poor understanding of the system we're monitoring (this never happens in tech, of course :)).
I don't see the point of testing constantly. It's just creating stress and probably most of the time, the tumor might be benign or it might be small and go away on its own.
And anyway, you have to die of something so for me cancer would just be a sign that time's up.
There’s a major difference between having insurance cover something (socialized cost, immediately drives up provider fees for bizarre reasons) and letting the market allow people to buy it themselves (individual cost, the market drives the cost down fast and hard). Notice the pattern with LASIK and GLP1 where lack of insurance coverage has counterintuitively made it cheaper and more accessible.
Let everyone who wants to pay get their scans! But don’t make me pay for you
1. collecting baseline info for later comparison is good
2. i can afford the money for the chance of early detection. Many cancers are symptomatic only in the latter stages. It does not hurt to check.