How often do full-body MRIs find cancer?

Yes, IF we know the numbers, that's the whole problem. Unprompted full-body MRI scans turn up a completely new probability distribution. We CAN'T know the numbers as of today, it takes decades of controlled studies to get them. (Which is exactly what doctors advocate for)

Even for something as studied as colon cancer it's still controversial whether mass colonoscopies are better than occult blood tests. US sticks to the former, Europe to latter. US have higher rates of polyp removal, higher rates of cancer detection, higher rates of surgeries and ... higher mortality rates than EU. Why this happens is being studied today, there are some early results. What is absolutely clear though is that higher detection rates don't automatically lead to better outcomes, it can easily be the opposite.

Or take something as simple as sunscreen. It's well-known that sun exposure for light-skinned people can cause cancer and sunscreen is advised. A few multi-decade studies have shown that while it indeed eradicates the skin cancer it also shortens the life expectancy by a few years.

Primum non nocere, doctors and scientists are unsure whether sunscreen should be applied at scale and you effectively call for mass biopsies and surgeries.

> and all of a sudden one of them starts changing in size at a rate disproportionate to its history, that's probably cause to dig a little deeper.

That sentence is doing a lot of heavy lifting.

- What's "disproportionate to its history"? Obviously something going from 1mm to 10cm is worth checking out, but what about something going from 1mm to 2mm? Might be a tumor, might be that the position is just slightly different.

- What about other less measurable factors? Example, border features. That's harder to measure and things like movement or different machines can change how the borders of a feature look. How do you know what's a baseline and what's not.

- How frequently do you run these scans? It's likely that if something "starts changing in size" suddenly it will start giving symptoms before you have your next scheduled scan.

> It's certainly not "throw more data at the problem". Instead it's about giving the data a time axis with some decent fidelity.

It's definitely throwing more data at the problem, and you're assuming that it's viable to give "a time axis with decent fidelity". MRIs are much more complicated to interpret than people think, and screening is a much harder problem too. There are a lot of studies testing MRI imaging as a screening technique (among other techniques) and they don't always show an increase in survival rates.

Please just read this article - https://jamanetwork.com/journals/jamainternalmedicine/fullar... It's funny that you instantly assumed that authors are stupid and did not think about this obvious pitfall. It's extra funny that you also accuse them of jumping to conclusion without actually reading the article.

> Even assuming your statement is true,

It is true. You need only trouble yourself to search. Here's a recent paper, for example: https://jamanetwork.com/journals/jamainternalmedicine/articl...

> if what is detected is small enough for that there's no reason "treatment" can't just be monitoring it's size with follow-up scans.

This is false—it is exactly what the article is trying to convey. There is a risk to any test, and one of the major risks for imaging is getting treatment for things that would never cause symptoms or require intervention.

> The people arguing against routine MRI scans are the checklist people!

Are they? They seem to be exactly the same set of people who resisted them ( https://pubmed.ncbi.nlm.nih.gov/22069112/ ).

> The argument being made here is about full body MRI scans: doing a dragnet sweep looking for neoplasms anywhere and everywhere. Not the same thing!

It's exactly the same thing, but on a larger scale. Yes, it will likely require at least some adjustment to the standards of care and development of more stringent criteria for follow-up procedures. But we're already talking about fine-tuning, rather than something fundamental.

Here's a study from one of the providers:

> 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. Of these cancers, 68% didn't have targeted screening tests and 64% were localized when detected. The company says it finds possibly life-threatening conditions in 1 in 20 people.

So we're talking about the real-world 4% rate for biopsies, with about 50% false positive rate. This is not that far removed from the current clinical 30% false positive rate. And this is far from the apocalyptic scenarios of multiple biopsies for every patient.

And the psychological burden appears to be modest: https://pubmed.ncbi.nlm.nih.gov/33279799/

While the negatives cited by doctors are:

> To date, no study has been performed that rigorously investigates the impact on disease-specific survival following whole body MRI in asymptomatic patients without specific risk factors, and no study has been performed to confirm that a ‘negative’ whole body MRI excludes significant disease 5 or more years’ later.

I read most of the studies that are cited here: https://www.ranzcr.com/college/document-library/2024-positio... And I have not found a single one that had anything really negative about the MRI consequences. And half of them are outright positive endorsements: https://pubmed.ncbi.nlm.nih.gov/33216779/

The only real remaining argument is cost effectiveness of MRI, especially for government-based healthcare. It is a valid argument, but it's beside the point for people who are self-paying. And it's also missing the implications of economy of scale.

So I'm pretty sure in this particular case the geeks indeed know more than doctors.