Sporadic Medullary Thyroid Cancer

Abstract

Medullary thyroid cancer (MTC) is a neuroendocrine tumor of the parafollicular or C cells of the thyroid gland. It accounts for approximately 1–2% of thyroid cancers. The production of calcitonin is a characteristic feature of this tumor. Most of the MTCs are sporadic whereas 25% of cases are familial as part of the multiple endocrine neoplasia type 2 (MEN2) syndrome. For sporadic MTCs, there are no germline RET mutations. The most common presentation of sporadic MTC is a solitary thyroid nodule. Systemic symptoms may occur due to hormonal secretion by the tumor. Most sporadic MTCs also secrete carcinoembryonic antigen (CEA). The diagnosis of sporadic MTC is usually made after fine needle aspiration (FNAB) biopsy in a patient who has a solitary thyroid nodule. Patients with sporadic MTC can be cured only by complete resection of the thyroid tumor with bilateral central neck lymph node dissection. For patients with the residual or recurrent disease after primary surgery or for those with distant metastases, the most appropriate treatment is less clear and still debatable.