"South Korea inadvertently illustrated this point when a government program, starting in 1999, offered free screenings for several common cancers. A thyroid-cancer screening wasn’t included, but many patients opted to add one for a fee. Between the early nineties and the early twenty-tens, rates of thyroid cancer soared fifteenfold—a development that would have been worrying, except that death rates from thyroid cancer never rose, and remained very rare."

https://www.newyorker.com/science/annals-of-medicine/will-a-full-body-mri-scan-help-you-or-hurt-you