Christie Aschwanden in FiveThirtyEight:
South Korea has a thyroid cancer problem. Incidence of the disease there has climbed 15-fold over the past 20 years — faster than any other cancer worldwide.
South Korea also has a thyroid cancer diagnosis problem. In a studypublished this month in the New England Journal of Medicine, researchers identified the cause of the country’s alarming epidemic: South Korea’s high-tech health care system. A national cancer screening program started in 1999 provides free screening for several common cancers, and thyroid cancer screenings are widely offered as a cheap add-on. As a result, the number of Koreans getting screened for thyroid cancer has soared.
That might sound great. But the good news about this epidemic — death rates from thyroid cancer have remained flat (and low), despite the skyrocketing number of diagnoses — is also the bad news. Ideally, screenings should lead to a decrease in cancer deaths. But not in South Korea.
In 2011, 40,000 South Koreans were diagnosed with the disease — more than 100 times the number of people there who die from it each year. The huge influx of new cases consists almost entirely of papillary thyroid cancers, an early-stage variety found in about one-third of all adults without symptoms. The idea behind screening is to find and treat early-stage cancers, preventing them from becoming deadly. When it works, the number of advanced cases and deaths go down as early diagnoses rise…