After South Korea ran public campaigns about thyroid cancer in 2014, a lot fewer people got surgery for it—down by about a third in just one year. This makes people think that talking more about overdiagnosis might help stop unnecessary surgeries.

In South Korea, more people were diagnosed with tiny thyroid lumps between 1999 and 2008—not because more people got sick, but because doctors started scanning for them more often with fancy tests.

In South Korea, between 1999 and 2008, doctors started finding a lot more tiny thyroid cancers—so many that the overall number jumped more than six times. But almost all of these were very small tumors that probably wouldn’t have caused any harm if left alone.

In South Korea, more and more people started finding thyroid cancer through routine scans between 1999 and 2008 — and this happened right after doctors began using ultrasound machines much more often thanks to new health rules.

In South Korea, more people are being told they have thyroid cancer than before, but not fewer people are dying from it — which means many of those new diagnoses might be for cancers that wouldn’t have hurt them anyway.

In South Korea, most of the rise in thyroid cancer diagnoses between 1999 and 2008 was from tiny tumors that almost never kill people — doctors were just finding them more often, not because more people were getting deadly cancer.