Letters Section Editor: Robert M. Golub, MD, Senior Editor.
In Reply: Dr Zhang and colleagues question why we consider the dramatic increase in thyroid cancer incidence to represent overdiagnosis, ie, the detection of cancers that would have otherwise never become apparent during life. Consider the alternative explanation—that the increase in incidence is real. In arguing this case, a number of questions arise. First, why is the increased incidence confined to early-stage cancers that are, on average, considerably smaller than those detected in the past? Second, why does the increase solely involve the cell type (papillary) that has proven to be a common autopsy finding in patients not known to have thyroid cancer during life? Finally, if the increased cancer incidence is real, why has the thyroid cancer mortality rate not changed?
Welch HG, Davies L. Changing Incidence of Thyroid Cancer. JAMA. 2006;296(11):1350. doi:10.1001/jama.296.11.1350-b