> Specifically, the U.S. has the best cancer survival rates in the world.

This is a misunderstanding of what "5 year survival rate" means. You're missing "lead time bias", and "over diagnosis bias".

From Risk Savvy by Gerd Gigerenzer

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While running for president of the United States, former New York City mayor Rudy Giuliani said in a 2007 campaign advertisement:1

"I had prostate cancer, 5, 6 years ago. My chance of surviving prostate cancer—and thank God, I was cured of it—in the United States? Eighty-two percent. My chance of surviving prostate cancer in England? Only 44 percent under socialized medicine."

For Giuliani, this meant that he was lucky to be living in New York and not in York, since his chances of surviving prostate cancer appeared to be twice as high. That was big news. It was also a big mistake. Despite the impressive difference in survival rates, the percentage of men who died of prostate cancer was about the same in the United States and the UK.2 How can survival be so different when mortality is the same?

The answer is that when it comes to screening, differences in survival rates don’t tell us anything about differences in mortality rates. In fact, over the past fifty years, changes in five-year survival for the most common solid tumors had no connection with changes in mortality.3 There are two reasons.

How Rudy Giuliani Was Misled

The first reason is called lead time bias. Imagine two groups of men with invasive prostate cancer. The first consists of men in Britain, where screening for prostate-specific antigens (PSA) is not routinely used and most cancer is diagnosed by symptoms. The second group is made up of men in the United States, where routine use of the test began in the late 1980s and spread rapidly, despite the lack of evidence that it saves lives.

In the British group, prostate cancer is detected by symptoms, say at age sixty-seven (Figure 10-1 top). All of these men die at age seventy. Everyone survived only three years, so the five-year survival is 0 percent. In the U.S. group, prostate cancer is detected early by PSA tests, say at age sixty, but they too die at age seventy (Figure 10-1 bottom). According to the statistics, everyone in that group survived ten years and thus their five-year survival rate is 100 percent. The survival rate has improved dramatically, although nothing has changed about the time of death: Whether diagnosed at age sixty-seven or at age sixty, all patients die at age seventy. Survival rates are inflated by setting the time of diagnosis earlier. Contrary to what many people have been told, there is no evidence that early detection and subsequent treatment of prostate cancer prolongs or saves lives.

The second reason why survival rates tell us nothing about living longer is overdiagnosis bias. Overdiagnosis happens when doctors detect abnormalities that will not cause symptoms or early death. For instance, a patient might correctly be diagnosed with cancer but because the cancer develops so slowly, the patient would never have noticed it in his lifetime. These cancers are called slow-growing or nonprogressive cancers.4 PSA screening detects both progressive and nonprogressive cancers but, like most other cancer screening tests, cannot tell the difference between them. Figure 10-2 (top) shows 1,000 British men with progressive cancer who do not undergo screening. After five years, 440 are still alive, which results in a survival rate of 44 percent. Figure 10-2 (bottom) shows 1,000 Americans who participate in PSA screening and have progressive cancer. The test, however, also finds 2,000 people with nonprogressive cancers—meaning that they will not die from them. By adding these 2,000 to the 440 who survived progressive cancer, the survival rate leaps to 81 percent. Even though the survival rate increases dramatically, the number of men who die remains exactly the same.