Full-Body MRIs Promise To Detect Disease Early. Do They Work?

17:02 minutes

A male patient in blue scrubs lies on a table with his head inside the large cynlinder of a blue and white MRI machine. A female doctor in a white coat stands next to him in with her right hand on the machine's buttons.
A doctor and patient use an MRI machine. Credit: Shutterstock

The latest trend in celebrity health care is full-body MRI scans, with influencers like Kim Kardashian endorsing them. These scans aren’t covered by health insurance, and run over $2,000 out of pocket. 

Typically, a new diagnostic tool is marketed to doctors and radiologists. But companies like Prenuvo are now marketing directly to consumers. They claim that their scans will catch early signs of cancer, aneurysms, liver diseases and even multiple sclerosis.

It’s an appealing promise. If you can afford it, wouldn’t it be nice to catch cancer super early? Could it even save your life? Unfortunately, it’s more complicated than that. Simply put, the potential harms far outweigh any possible benefits of such a scan. 

Guest host Flora Lichtman separates fact from fad with Dr. Rebecca Smith-Bindman, professor of epidemiology and biostatistics at University of California, San Francisco’s School of Medicine, and director of the Radiology Outcomes Research Laboratory, based in San Francisco, California.

Further Reading

Segment Guests

Rebecca Smith-Bindman

Dr. Rebecca Smith-Bindman is a professor of Epidemiology & Biostatistics at University of California – San Francisco’s School of Medicine, and director of the Radiology Outcomes Research Laboratory, based in San Francisco, California.

Segment Transcript

FLORA LICHTMAN: This is Science Friday, and I’m Flora Lichtman. The latest trend in celebrity health care– full-body MRI scans. Celebrities like Kim Kardashian are endorsing them. They aren’t covered by health insurance and run over $2,000 out of pocket. Typically, a new diagnostic tool is marketed to doctors and radiologists.

But companies like Prenuvo are marketing directly to consumers. They claim that their scans will catch early signs of cancer, aneurysms, liver diseases, and even multiple sclerosis. And it’s an appealing claim. If you can afford it, wouldn’t it be nice to have that peace of mind, catch cancer super early, potentially even save your life? But is that claim even true?

Here to separate fact from fad is my guest, Dr. Rebecca Smith-Bindman, Professor of Epidemiology and Biostatistics at the University of California, San Francisco School of Medicine and the Director of the Radiology Outcomes Research Laboratory based in San Francisco, California. Welcome to the show.

REBECCA SMITH-BINDMAN: Thank you so much for inviting me.

FLORA LICHTMAN: OK, so celebrities make dubious health claims all the time. I am looking at you, goop jade egg. Why should we be paying attention to these full-body MRI scans?

REBECCA SMITH-BINDMAN: I think many of the bogus things that celebrities suggest people should do for wellness are pretty harmless in and of themselves. They may not have any value, but they also don’t cause real harm. Where this is a medical test and using a medical test, a procedure that has some potential benefit but a lot of potential harms, in such a way can lead to really bad patient outcomes. And I think that doesn’t come across in the advertising for these scans.

FLORA LICHTMAN: I think most people would be tempted to think like, well, what’s the harm of getting an extra scan? So can you lay out what the harms are?

REBECCA SMITH-BINDMAN: Absolutely, and I agree with you. I think if full-body MRIs could in fact find disease early and prevent them from becoming symptomatic, that would be really valuable. And the problem is that there are many potential harms from using these tests. And those harms will lead to a lot more medical interventions.

So the first harm is that you’ll find things on these scans that really just represent normal variation between patients. I think the best analogy that I could use are moles on the skin. Many people have lots of moles on the skin. And when we see them, we notice them, but we know that they’re not important. And we don’t trigger anything else, such as a biopsy of them.

On the other hand, when we have these kinds of moles, or growths, or nodules, or areas of enhancement at different parts of the body, like the liver, the thyroid, the ovaries, the kidneys, we don’t know what they are. We don’t know that they’re harmless. And thus, once you find such a nodule from this kind of screening MRI, you then need to do other tests to make sure that it’s not the feared cancer that you’re looking for.

And those other tests include tests like PET/CT scanning, which deliver radiation, or tests such as using a biopsy to find out what it is. And in the end, those false positives will be put to rest but only after an enormous amount of other tests, other procedures, anxiety in the patient, thinking that they might have cancer when, in fact, they don’t. And for full-body screening MRI, about 20% to 40% of patients will have a false positive, where basically you have to then do something else to ensure it’s not real. So that’s one pretty big harm.

FLORA LICHTMAN: Right, right. And then once you find something abnormal, it sounds like there are many, many more tests that you can’t ignore it, basically. You don’t know if it’s harmful or not, but then you can’t ignore it.

REBECCA SMITH-BINDMAN: You’re kind of between a rock and a hard place. And even if the physicians say, oh, we see these a lot, I’m not concerned about it, and you ask, well, what is the chance that it’s cancer, to get some sort of hard number, those numbers don’t exist. And part of the problem with the MRI technology is it’s so good at seeing things that it’s so surpasses our knowledge base of whether or not they’re harmful. But there’s one other harm that’s, I think, you can think about similar to false positives but actually is quite different.

And that’s basically finding early cancers that would never have progressed or ever hurt the patient. As our greater understanding has developed, we realize that there are lots of early cancers in almost every part of the body. The one area that I think there is general understanding of this is prostate cancer. There’s an enormous amount of prostate cancer that’s never going to hurt the men. Even though it’s cancer under the microscope, it doesn’t behave as an aggressive disease that will hurt the patient.

And the more you do surveillance and screening, the more of these findings of early stage cancer that you find. So breast cancer, thyroid cancer, renal cancer, prostate cancer, there are lots of lots of early-stage cancers. Once you find the cancer, at first it just appears as a nodule, so you have to go through the invasive evaluation to decide, OK, is this a false positive? That’s not anything. Or is it cancer?

Once it’s found to be cancer, then the patient will undergo complete treatment for the cancer. That might be chemotherapy, or surgical resection, or radiation, or all of the above. And for most of the cancers that you find through this opportunistic screening, those cancers were never going to hurt the person in the first place. But once you diagnose the cancer, you’re obligated to treat it because you can’t fully distinguish it from one that’s going to be aggressive.

FLORA LICHTMAN: Wow. That’s so surprising to me, that I might have precancers in my body right now, but I don’t need to worry about them. This is like great news.

REBECCA SMITH-BINDMAN: That’s why it’s so complicated. That’s why it’s so complicated. In fact, that is exactly the case. And for some cancers– one very good example is breast cancer– there’s a very early cancer called ductal carcinoma in situ. In situ means it hasn’t invaded outside the cell, and there’s a movement to rename ductal carcinoma in situ with a name that doesn’t include cancer in it because it’s kind of precancer and as a way to make patients understand that this is different than cancer.

If you screen the whole body at the same time, which is what these scans specifically do, you’re going to find so many of those precancers or early cancers that are not indolent, that don’t hurt the patient. And yet so many patients will be labeled with cancers. And of course, that will lead to enormous expense. You mentioned the expense of the first test, which is, obviously, a real amount of money for people to have to shell out for this test.

But in fact, the real costs of this technology are orders of magnitudes greater. All the costs come from the subsequent diagnostic tests and treatment. And none of that is borne by the person individually. It’s borne more broadly by the health care system and our insurance premiums.

FLORA LICHTMAN: You mentioned this briefly. But how big is the risk of radiation exposure from these scans? Could you be actually manifesting the disease you’re worried about getting?

REBECCA SMITH-BINDMAN: So the MRI itself uses what’s called nonionizing radiation. Basically, it’s lower-dose radiation that is not known to cause cancer. But what does cause cancer is the subsequent diagnostic tests, such as PET/CT. And those exams have enough radiation that they will absolutely cause cancer in some patients.

I recently collaborated on a editorial around liquid biopsy. It’s sort of another test where you’re screening the blood for all kinds of cancers. And for that test, you don’t know anatomically what part of the body is affected if you get a signal from the blood test. So you have to do a full-body scan, like a PET/CT, to find the cancer. And in that case, for the analysis that we completed for the editorial, if a million patients undergo this liquid biopsy test, about 37 patients would have cancers caused by the follow up PET/CT.

From the MRIs, I don’t know the number of patients who will end up having a PET/CT. But my guess it will be even higher than the 1% who are estimated in the liquid biopsy. So when I talk about the harms of subsequent exams, it’s not a theoretical risk. It’s a real risk. Many, many patients will have a signal on the MRI, and they will have to do something else. And among the most common something else tests, it will be PET or PET/CT, and that will cause cancer in some patients.

FLORA LICHTMAN: What about outside of full-body screenings? Are doctors ordering more imaging generally? Are we seeing the use of screenings go up in hospitals or in doctors offices?

REBECCA SMITH-BINDMAN: I want to separate that into two separate answers because you used the word screenings. So the use of screenings is generally used in patients who don’t have symptoms. And so we think about screening tests that have been studied, things like mammography for breast cancer, or, I mentioned, CT scanning for lung cancer, or scanning of the abdomen for colon cancer. In terms of screening asymptomatic patients, there has not been a huge rise in the use of testing. And in fact, there are efforts to try to encourage physicians to do more screenings of the ones that have been studied and we know are beneficial.

On the other hand, the use of diagnostic imaging, where the patient has a symptom and we’re not sure what’s causing the symptom, the use of imaging in that setting continues to rise briskly. So CT scanning is sort of the bread and butter of imaging. And the rates of CT imaging completely have a stable increase over time. We currently obtain in the US in the ballpark of 90-million CT scans a year, so a really huge number. And that number has increased year after year.

FLORA LICHTMAN: You’ve studied thyroid cancer. What can that example help us understand about the benefits and drawbacks of imaging?

REBECCA SMITH-BINDMAN: I think there are several reasons thyroid cancer is a great example because thyroid cancer, in general, not for everyone but in general tends to be a rather indolent, slow-growing disease. If you have to pick a cancer to have, thyroid cancer is generally the cancer that physicians are willing to have because it’s just not that aggressive. At the same time, there are so many nodules in the thyroid gland. So probably in the ballpark of 50% of patients have some nodule in their thyroid gland.

And it’s not that easy to tell which nodules mean nothing– they are completely benign– and which nodules may harbor cancer. And thus, if you screen 1,000 patients with thyroid imaging, maybe 500 patients will have a nodule. 200 to 300 will have a nodule where you’re really not sure if it’s cancer. And only one of those patients will actually have a cancer that matters, that you want to find. And thus, you can imagine, if you screen a lot of people and if you’re not finding the aggressive cancers that you really want to find early, you won’t have an impact on thyroid mortality. Mortality won’t change. But the diagnosis of cancer will go up steeply because there’s so much indolent cancer in the thyroid.

And the experience in South Korea shows that exactly. So they instituted basically nationwide screening for thyroid cancer. They ended up finding so many more thyroid cancers, so the rate of diagnosis of thyroid cancer went up steeply. And the mortality didn’t change at all. Basically, they had no impact on the progression of disease. For screening to be worthwhile, you have to both find the cancer early, and your intervention has to prevent it from becoming an aggressive cancer. And there was no such benefit in South Korea, and they’ve stopped screening.

In the US similarly, the number of cases of thyroid cancer diagnosed annually has gone up really dramatically in the US because of greater use of diagnostic imaging. And yet we, too, have not seen any reduction in mortality from thyroid cancer. And that’s a telltale relationship between the number of cancers and the death from the cancers that reflects overdiagnosis.

FLORA LICHTMAN: If you’re just joining us, I’m talking with Dr. Rebecca Smith-Bindman from UC San Francisco about why more cancer screening doesn’t always lead to better outcomes for patients. This is Science Friday from WNYC Studios.

We know preventative screens are effective in catching some types of early cancer. I’m thinking of breast cancer and colon cancer. But even this seems tricky. I know the breast cancer screening age has flip flopped a little bit in recent years. Why is it a hard question to answer when screening should start and how frequent they should be? Why do the recommendations keep changing?

REBECCA SMITH-BINDMAN: It is a little bit frustrating that the recommendations keep changing because breast cancer is one of the areas that there have been a lot of meaningful studies. We’ve had many randomized trials that show that there is a benefit in screening women with mammography. The challenge, however, is how to balance the potential benefits against the potential harms.

And most of the disagreements about what ages to screen are based on how do we weigh the possible benefits and possible harms. And in younger aged women in the mammography discussion, women in their 40s, have relatively less benefit compared to the older women who are screened and have more harms in terms of the false positives that we talked about and even overdiagnosis. And so the trade off is how we decide that we want to balance the benefits and harms.

And different groups put different weights on the false positives versus the sensitivity to find cancer. And so mammography is absolutely a better test in women in their 60s than in women in their 40s. But whether or not that means we should not do mammography in women younger versus the older age bracket depends on how you value finding the cancer early but causing many, many, many women to have procedures that don’t lead to any diagnosis. And we don’t really know if we can just wait a few years and begin at age 50 and see the same benefit.

But I think what’s really interesting is that there are a number of screening tests that have been studied and that lead to pretty convincing results that there’s benefit. And yet to introduce a full-body scan that screens for a dozen body regions at the same time without a single stitch of evidence that that will lead to improved outcomes is really where the problem lies. This is not introducing something that perhaps has no value but is harmless. This is introducing something that potentially has great harm.

And it would not be a difficult study to do, to do a randomized trial, to figure out if this test is as valuable as these companies are suggesting. And to introduce it without that is really an extreme example of medical care run amok.

FLORA LICHTMAN: This has been so fascinating. Thank you so much for coming on the show and sharing your expertise.

REBECCA SMITH-BINDMAN: It’s been my pleasure. Thank you so much for helping people understand why this test is simply not a panacea.

FLORA LICHTMAN: Dr. Rebecca Smith-Bindman, Professor of Epidemiology and Biostatistics at the University of California, San Francisco School of Medicine and Director of the Radiology Outcomes Research Laboratory based in San Francisco, California.

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