RET can be aberrantly activated by mutations and chromosomal rearrangements (Figure 1); both of which has been linked to the process of oncogenesis in different tumor types.2 Initial discoveries were made in patients with thyroid cancer who had multiple endocrine neoplasia syndrome, but later evidence suggested a role of RET alterations in other sporadic cancers as well.10, , , –14RET mutations are relatively more frequent, but RET fusion-positive cancers represent a distinct molecular entity that defines a unique clinical subtype.15,16. This evidence concerns the gene RET and thyroid cancer.