ScienceDaily (May 5, 2009) — It’s a medical mystery that has been developing for at least a decade: thyroid cancer—not breast, prostate, lung, or colon cancer—is the fastest increasing cancer among women and men in the United States.

And scientists don’t know why.

In fact, according to new data from the National Cancer Institute (NCI), thyroid cancer diagnoses have increased at a rate of 6.5 percent a year from 1997 to 2006.

The alarming trend has largely gone...