The more you look, the more you'll find. We've known for almost fifty years that huge numbers of men have prostate cancers that sit there quietly, doing no harm until eventually you die with the cancer rather than from the cancer. Absent screening, you don't even know it's there. But of course once you start screening, huge numbers of extra cancers appear to be present; hence it looks like an alarming increase in incidence. Which, if you're not careful, can be blamed on all sorts of features of modern life from global warming through diesel fumes to sunspots (ok, I'm joking).
Prostate cancer is the most famous example, but the same applies to skin cancer (all those pigmented lesions), kidney, breast and, to come to today's topic, thyroid cancer.
But now it seems that among all the noise of increased detection from more widespread use of better imaging, there may be a small signal of true increase in incidence. It's not a big effect but it does remind us that truth ('it's all due to increased diagnosis') is never simple. We must be subtle.