Does the U.S. Over Diagnose Cancer?
Ezra Klein challenges the notion that patients in the U.S. get better cancer treatment than patients in other developed countries. Klein was writing in response to the Commonwealth Fund’s comparison of health systems in eleven developed countries. As I noted previously, one problem with this survey is that there is no apparent relationship between ranking on the survey and health outcomes. Although the U.S. does poorly in the survey, it does well in health outcomes, especially cancer outcomes.
Or maybe not, according to Klein:
Most of the studies that highlight America’s skill in treating cancer do so by measuring survival rates — that is to say, they measure how many people survive for a certain number of years after the cancer is diagnosed. So if a certain cancer kills 50 percent of people within five years, then the five-year survival rate is 50 percent.
The problem here is simple: survival rates don’t necessarily measure when people die. They also measure when they’re diagnosed — and sometimes, that’s all they measure.
“Let’s say there’s a new cancer of the thumb killing people,” writes Aaron Carroll, a professor of pediatrics and assistant dean at Indiana University’s School of Medicine. “From the time the first cancer cell appears, you have nine years to live, with chemo. From the time you can feel a lump, you have four years to live, with chemo. Let’s say we have no way to detect the disease until you feel a lump. The five year survival rate for this cancer is about 0, because within five years of detection, everyone dies, even on therapy.”
Carroll goes on to imagine a remarkable machine: “a new scanner that can detect thumb cancer when only one cell is there.” Congress immediately orders that every American be scanned for thumb cancer. “We made no improvements to the treatment,” he writes. “Everyone is still dying four years after they feel the lump. But since we are making the diagnosis five years earlier, our five year survival rate is now approaching 100%!” That’s how survival rates can mislead.
Klein goes on to report that actual death rates (in the U.S. population) have not really changed for many cancers, despite much greater detection. Further, this epidemic of over diagnosis can cause harm, because people will undergo surgery who don’t need it. (This argument is made thoroughly in Gil Welch’s Overdiagnosed.)
Although this argument is not trivial, I find it hard to accept. First, almost all stories of harmful treatment concern breast cancer or prostate cancer. There are lots of other cancers, but their victims do not have the benefit of early screening. For example, lung cancer is often diagnosed after a person has a troubling cough. Only recently did the American Society of Clinical Oncologists suggest annual screening with low-dose computed tomography (LDCT) for smokers and former smokers at high risk for developing lung cancer. Surely, opponents of “over diagnosis” do not want us to “uninvent” mammography, and have women wait until lumps appear before they are diagnosed.
Also, early detection has a social benefit, because it leads to greater learning about the nature of a disease, which leads to better therapies. For example, I cannot imagine how we would have any genomic medicine if organized medicine had decided that it did not want to push back the time of diagnosis before symptoms appear.
Further, it is not clear what “over diagnosis” has to do with “universal health care”. Klein cites a study by Tomason and colleagues, which compares U.S. with international survival rates. However, that study did not describe which health insurance the U.S. patients had. There are very few comparisons of cancer outcomes that compare U.S. uninsured and insured patients. Linda Gorman reviewed one that showed that privately insured breast-cancer patients had earlier diagnosis and better outcomes than Medicaid and uninsured patients. So, score one for private health insurance and early preventive screening.
Finally, as Klein notes, the alternative to measuring survival is measuring death rates. However, that ignores all medical interventions. Knowing how many people die of a certain cancer in a population tells us nothing about the state of the healthcare system. For such a purpose, survivability appears to be the superior of two limited measurements.
I like the idea of the breathalyzer for lung cancer. There are also studies of training dogs to smell cancers. It’s been suggested that mass spectrometry of bodily fluids could detect cancers and other health issues.
How does that work? Do you schedule an appointment at a diagnostic imaging center like when you get a CT (i.e. “cat scan”)? Or do you have to go to a veterinary clinic for a “dog” scan?
I think they bring in the K-9 unit police dogs in to diagnose you.
Would you prefer a lab report or a CAT scan? (Get it?)
Are we to seriously believe that detecting cancers earlier isn’t a benefit to the longevity of patient involved? If Klein really believes that, then there is no reason to screen anyone for any cancer, right? My sense of the article is that it is an attempt to minimize a success of the US healthcare system, but is doing so in an idiotic fashion.
That seems to be what Klein advocates, weirdly enough. But there are plenty of people who are seeking ways to cast the pre-ObamaCare US healthcare system as majorly flawed so that the public will become more accepting of the law.
Of course earlier detection is in everyone’s best interest, but there are now incentives to have more tests and procedures “approved” in order to control costs. Hence, suddenly we have an “over diagnosis” problem.
As I read Klein, he saying that if early intervention strategies add sufficiently little to the prognosis, then early detection can improve your survival rate without accomplishing anything of real, measurable value.
This really shouldn’t be controversial.
But it all rests on the assertion that early detection does nothing for the prognosis. I would need to see some really strong evidence for that assertion like, for example, comparisons of patients caught in an early stage vs those caught late. I find it very difficult to believe there is no benefit to catching it before metastasis, at the very least.
But he made no such assertion!
But he does when he claims that death rates are “unchanged”. There is no support for that claim, and it borders on being a non sequitur.
The effect under discussion apparently has a name: “lead-time bias”. This guy thinks that it makes survival rates tricky to interpret:
http://www.sciencebasedmedicine.org/the-early-detection-of-cancer-and-improved-survival-more-complicated-than-most-people-think/
I agree with you that if cancer is treatable, the stage at which it is caught must generally make a difference. I am starting to think that the survival rate questions have more to do with “early” vs “very early”. That said, I had a hard time finding good material on this subject – and I still haven’t found any reference which actually attempts to estimate the magnitude of this effect on, for example, US vs UK comparisons. If I find anything I’ll post it here.
You might be surprised. Watch:
http://videocast.nih.gov/Summary.asp?File=14797&bhcp=1
I didn’t have time to watch all of the hour-long video, but it raises some interesting point. It is intuitive that early detection of cancer is better than late detection. That is certainly true to lung cancer and pancreatic cancer — two cancers that are deadly because their lack of symptoms makes late detection the norm. On the other hand, prostate cancer is often caught relatively early. Yet, most men die with prostate cancer rather than die of prostate cancer.
I’ve read that our bodies have millions of cancer cells at any given time. Most will be harmless. Maybe some day cancer cells will be thought of like bacteria was 100 years ago. Throughout history, people died of common infections but antibiotics made death from bacteria a rarity for all but the very young and very old.
Cancer is not one disease. The multitude of cancer types, even from the same organs, may act differently depending on what cells are involved. Thus, it is difficult to make a blanket statement which covers all types of cancer.
“Klein goes on to report that actual death rates (in the U.S. population) have not really changed for many cancers, despite much greater detection”
Regardless if death rates have not proven to statistically change death rates, I think it is a knee jerk reaction to conclude that there is rampant over-diagnosing of cancer in the States.
You can’t argue with a communist wanna be like Ezra Klein. If he had his way, the US would be like a 1950s USSR. He’ll twist data around in any way to denigrate the US and prop up his quasi communistic political buffoonery.
Aaron Carrol writes: “Everyone is still dying four years after they feel the lump.” But let us say the cancer is eliminated by treatment before the lump appears. Then Aaron Carroll who seems to be invested in bashing American healthcare would argue that the cure (no lump) proved we were doing unnecessary scanning of the thumb. You cannot win with people that can only see one side of the coin.