Invited commentary: medullary thyroid cancer: the importance of RET testing.

In this issue of Surgery, Bugalho and colleagues from Portugal, present their experience with RET testing of patients with sporadic and familial medullary thyroid carcinoma (MTC). Although their targeted approach to RET testing for patients in whom the mutation status is unknown (presumed sporadic MTC) is not often practiced in this country (where sequencing of exons 10, 11, and 13 to 16 is commonly performed), their paper serves to emphasize the importance of ordering RET gene testing on all patients with MTC. At present, knowledge of the RET mutation status and disease extent is required to determine the correct operation for any patient with MTC. Therefore, all surgeons caring for patients with presumed sporadic or inherited MTC need to know how to obtain genetic testing of the RET proto-oncogene. Inherited MTC can occur as part of multiple endocrine neoplasia type 2 (MEN 2) syndrome. MEN 2 is an autosomal dominant inherited cancer syndrome with 3 main subtypes: MEN 2A, MEN 2B, and familial MTC (FMTC). These clinical subtypes differ from each other in the spectrum of endocrine involvement and the biologic behavior of MTC. MEN 2A is clinically defined by the presence of MTC and either pheochromocytoma or hyperparathyroidism (or both) in a single individual, or the presence of 2 or more tumor types in multiple relatives of a single family. MEN 2B is characterized by MTC and pheochromocytoma, without hyper-