Narrative review of neck reinterventions for medullary thyroid carcinoma: indications and outcomes

Objective: To discuss the cervical recurrence risk factors of medullary thyroid carcinoma (MTC) and the indications, recommended surgical strategy and outcomes of cervical reintervention. Background: Unlike differentiated thyroid carcinoma, MTC is not sensitive to radioactive iodine, thus making surgery the cornerstone of the treatment of these patients. Initial surgery consists of total thyroidectomy with bilateral central compartment (level VI) lymph node dissection, being lateral lymphadenectomy indicated whenever macroscopic cervical lymph node metastases are present. However, up to 50% of patients with presumed curative surgery have persistent elevated serum calcitonin levels, in most of the cases due to inadvertent residual malignant tissue or metastases, and 10–25% develop cervical recurrence. Nodal disease is the main form of structural recurrence, with a median time until diagnosis of 4 years since initial surgery. Both serum calcitonin levels and the evidence of macroscopic recurrence/persistence should be used to guide the indication for reoperation. If biochemical cure has not been achieved and there is no evidence of structural disease, a watch-and-wait approach might be adopted. However, surgery is indicated in the presence of structural recurrence or after a sub-optimal initial procedure. Metastatic workup is necessary before reoperation as the extent of the disease will guide the surgical strategy. This metastatic workup consists mainly in imaging techniques [computed tomography (CT)-scan, magnetic resonance imaging (MRI), bone scintigraphy and neck-ultrasound (US)], nuclear medicine techniques [positron emission tomography (PET)/CT] or invasive procedures such as diagnostic laparoscopy. Neck reintervention is associated with a higher risk of complications than during primary surgery, mainly recurrent laryngeal nerve injury, permanent hypoparathyroidism, and thoracic duct leak, and therefore reintervention should be carefully planned and performed by experienced endocrine surgeons. Reintervention can be planned either with a curative intent or as a palliative procedure. If planned with a curative intent, a compartment-oriented lymph-node dissection is the recommended surgical strategy, and the goal should be achieving biochemical cure. Methods: Narrative review of articles published between 1990 and 2021. An additional review of the articles referenced in the bibliography of the included articles was performed. The search was conducted in PubMed and Web of Science. Conclusions: Reintervention, even if associated with a higher morbidity, does not imply a worse overall prognosis if biochemical cure is achieved. On the contrary, it can be planned as a palliative procedure aimed at minimizing complications derived from compromise of vital cervical structures such as airway, esophagus, or major vessels.