“ 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.
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 prostate and do NMR on lesions you find.
Lets say someone has lower urinary tract symptoms. And is 60 years old. An MRI could visualize as well as do a analysis that would otherwise require a biopsy. With the raised prior you can be quite sure suspicious lesions are cancerous.
Similarly for CNS tumours. Where fine detail. Subtle diffusion defects can mark csncers you couldn't even see if you cut the person open.
No sensible doctor would give you a whole body CT unless there was a very good reason. That very good reason is probably "we already think you have disseminated cancer". That pushes the prior up.
And less so for a PET/CT. Lets flood you with x-rays and add some beta radiation and gamma to boot!
The danger of an unnecessary CT/PET is causing cancer, the danger of an unnecessary MRI chasing non existent 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)
> I do take slight offense to the following at the top of my results:
No offense for me, just confusion. One of the status reports started as follows:
> OptionOfT is a very pleasant 36-year-old gentleman 6 weeks status post left anterior total hip arthroplasty done by Dr. _ on _.
I asked my wife whether I was particularly friendly (I sometimes fail to adjust my demeanor in certain situations).
She said: nah, they write that for everybody.
“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.
Basically half of all men have some early form of prostate cancer. Now that does not show up very well on an MRI, but there are quite a few diagnosis like that that are not necessary life saving.
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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.
This guy has never heard the term 'scanxiety'. Go ask what it means on a cancer forum. The real OG's are the VHL folks. Bet we have a few here on this thread. Respect.
I have, it's the fault of how medicine is practiced to reduce cost. It's completely avoidable, you can just not tell people their scan results if they have no symptoms and the detection is less than 95% likely to be cancer. This is strictly better than the status quo because the only difference is some people who almost certainly have cancer learn that they have cancer and nothing else changes
Again, you're assuming the only downside of a routine scan is anxiety. No, the real downside is that you'll trigger needless invasive procedures.
How can you trigger an invasive procedure if nobody learns the result of the scan?