Excellent piece on Prenuvo’s whole body scans by Dr. Dhruv Khullar in The New Yorker:
Doctors sometimes use a barnyard analogy to talk about the vast differences between cancers. A tumor can be a turtle, a bird, or a rabbit, depending on its speed and ability to escape; the goal of screening and treatment is to fence the cancer in. Turtles move so slowly that, fence or no, they’ll never make it out. Birds are so flighty that fences are irrelevant; even if you spot them, there’s no real way to stop them. Only the rabbits can actually be fenced in. By some estimates, at least a quarter of cancer diagnoses can be considered overdiagnoses. These tumors are turtles; they never would have left the barn.
South Korea inadvertently illustrated this point when a government program, starting in 1999, offered free screenings for several common cancers. A thyroid-cancer screening wasn’t included, but many patients opted to add one for a fee. Between the early nineties and the early twenty-tens, rates of thyroid cancer soared fifteenfold—a development that would have been worrying, except that death rates from thyroid cancer never rose, and remained very rare. Diagnosing these cancers wasn’t saving lives: almost all were papillary thyroid tumors, which are present in as many as a third of all adults and rarely cause problems. Nonetheless, tens of thousands of South Koreans had their thyroids removed and started taking lifelong hormone supplements. They’d fenced in turtles.
Excellent, accessible illustration of what screening is for and why more isn’t always better. There will always be happy individual narratives of people saved by screening even when, on the whole, a particular screening test is net harmful. Judging a population tool that results in society-wide costs based on individual unaggregated results is a fool’s game.
Quoting a scene from Scrubs, the most accurate medical television show of all time:
In a 2004 episode of the sitcom “Scrubs,” Bob Kelso, the chief of medicine at Sacred Heart Hospital, runs into a fellow-doctor, Perry Cox, in the hallway. “I am considering offering full-body scans here at Sacred Heart,” Kelso says. “What do you think?”
Cox looks appalled. “I think showing perfectly healthy people every harmless imperfection in their body, just to scare them into taking invasive and often pointless tests, is an unholy sin,” he says.
“Does sound a little sketchy ethically, doesn’t it?” Kelso says. “Thanks, Perry.”
It’s feasible there could be a future world where very frequent low-cost whole-body screening is helpful, particularly if the follow-up for turtles was nearly always just more low-cost whole-body screening and not something costly and/or invasive. But today, in our current strained inefficient system with its high costs–and its current players and their financial motives–this is unlikely to be the case.
3 Comments
Great article. Thank you for sharing.
Could you elaborate on your conclusion a bit more?
It seems to me that you’re suggesting that Prenuvo would ultimately serve to “[show] perfectly healthy people every harmless imperfection in their body, just to scare them into taking invasive and often pointless tests,” as Cox put it.
You referenced South Korea’s program 25 years ago that resulted in what might today be recognized as unnecessary thyroidectomies. If this same study were performed today in the US, do you think that less thyroidectomies would be performed, given what we know about papillary thyroid carcinoma?
I totally hear your argument that full body MRI scans in today’s medical environment will likely result in more healthcare visits for patients willing to pay for these scans, but how else can the US healthcare system shift towards a more preventative model without initiating some sort of program like full body MRI scans? This question, of course, assumes that the US should switch to a preventative model.
In the same vein, I’ve heard some radiologists claim that the future of primary care will be with a radiologist, as they believe that preventative medicine will begin with — or at least include — a full body scan, since virtually anyone who sees a doctor these days gets sent for imaging anyway.
Would love to get your thoughts on this!
Re: thyroids. While we recommend fewer biopsies than in the past, thyroid histologic sampling remains a diagnostic challenge, and we still biopsy too many benign nodules and treat too many indolent cancers. Many clinicians and patients also have difficulty stopping follow-up even when radiologists recommend stopping per guidelines. We would still massively overtreat, in my view.
Preventative health in this context, in terms of limiting harms and maximizing return on investment, would likely be in known preventative measures that influence the major causes of morbidity and mortality like cardiovascular disease, obesity, lung disease, drugs of abuse, etc. The assumption that earlier knowledge of often indolent cancer leads to better outcomes needs to be tested, not assumed. We know what kills most people that our system does not manage well, and this is not the low-hanging fruit. Screening can do real harm, so we need to keep our eyes open past the happy anecdotes.
I don’t think radiologists in the current era can or would stand in for primary care doctors. How things look in the future with widespread AI is anyone’s guess.