These results not only suggest the existence of new and more recent etiologic factors resulting in the change of molecular profiling and the increased incidence of thyroid cancer, but also imply that environmental or therapeutic radiation is not likely to be the major contributor, since as many as 80% of papillary thyroid carcinoma patients with radiation exposure carry RET/PTC chromosomal rearrangements [3, 29]. Here, RET is linked to differentiated thyroid carcinoma.