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 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.

There is no doubt that America screens for cancer more aggressively than any other nation. And there is no doubt that America catches more cancers, and catches them earlier, than any other nation. Since everyone knows that it’s easier to treat cancers when they’re caught earlier, it seems like that should mean America is better at treating cancer than any other nation.

“As a culture, we have been inundated with this message that early detection is the key,” Carroll said in 2014. “We want to know now if we have it. We think if we know we’ll have a much better chance of having a good outcome. And sometimes that is the case. But it’s rarer than people think.”

Perhaps the most famous example is mammograms. Almost everyone thinks mammograms save lives. One survey found that 50-year-old women think mammograms save 80 lives for every 1,000 screenings. But considerable evidence shows mammograms have been wildly oversold. A rigorous study of 90,000 women concluded that “annual mammography in women aged 40-59 does not reduce mortality from breast cancer beyond that of physical examination.” And the screenings have costs, too: 22 percent of the invasive breast cancers caught by mammograms were “overdiagnosed,” leading to expensive, scary, and potentially dangerous treatments for women who didn’t need them.

In response to the study, the Swiss Medical Board recommended the country phase out its breast cancer screening programs. (America’s recommendations around breast cancer screenings are all becoming more conservative, though they’re nowhere near giving up on the practice.)

That isn’t to say early detection never helps. It really does matter for colorectal cancer, for instance. But it doesn’t help for all cancers, and too much screening leads to dangerous overtreatment. In some cases, the America’s aggressive screening programs are saving lives. But in some cases, they’re certainly hurting people.

The simple measure: how many people die from cancer?

In recent decades, America has gotten much, much better at screening for cancers. But it hasn’t gotten that better at curing them. In “Preventing overdiagnosis: how to stop harming the healthy,” Ray Moynihan, Jenny Doust, and David Henry chart the rapidly rising diagnoses of various cancers  —the blue line  — against the actual death rates from those cancers. As you can see, the blue line rises like a rocket on each graph. The red lines are relatively flat. Disturbingly flat.


(“Preventing overdiagnosis: how to stop harming the healthy”)

A lot of those cancer diagnoses are picking up malignancies that will never cause symptoms, let alone death. But they make survival rates look a lot better.

“The best measure for progress against cancer is mortality rates,” said Ahmedin Jemal, vice president for surveillance and health services research at the American Cancer Society, in a 2014 interview. “Not survival rates, because they can be inflated by early detection.” The best measure, in other words, is those red lines.

The difficulty is that cancer mortality is affected by much more than just the health-care system. Prevention matters, as does environment, and lifestyle, and population. Some groups are simply more prone to cancers than others. Some national diets lead to more cancers than others. Brazil and Mexico have low cancer mortality, but no one would say that the Brazilian or Mexican health-care systems are the finest in the world.

Still, a straight look at cancer mortality shows America looks a lot like its peer nations — and certainly not like a country that often spends twice as much on health-care treatment. There is considerable variation among cancers — the U.S. looks fair on breast cancer and colorectal cancer mortality, but very bad on lung cancer mortality. The single greatest reason for cancer reduction in westernized countries in recent years is significant reductions in people who smoke. Even taking that into account, this graph from Carroll doesn’t show a country with low cancer mortality:


(Aaron Carroll/Incidental Economist)

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