Given the evidence that dedifferentiation of thyroid cancer was evolved from a subclone of WDTC and defects in DNA repair could play an important role in the dedifferentiation process (37, 38), subclonal BRAF mutation and clonal TP53 mutations may be the manifestation of tumor evolution and associated with aggressiveness of tumors. This evidence concerns the gene BRAF and thyroid gland carcinoma.