“A” strongly recommends

The recommendation is based on good evidence that the service or intervention can improve important health outcomes. Evidence includes consistent results from well-designed, well-conducted studies in representative populations that directly assess effects on health outcomes.

“B” recommends

The recommendation is based on fair evidence that the service or intervention can improve important health outcomes. The evidence is sufficient to determine effects on health outcomes, but the strength of the evidence is limited by the number, quality, consistency of the individual studies, generalizability to routine practice, or indirect nature of the evidence on health outcomes.

“B” recommends

The recommendation is based on fair evidence that the service or intervention can improve important health outcomes. The evidence is sufficient to determine effects on health outcomes, but the strength of the evidence is limited by the number, quality, consistency of the individual studies, generalizability to routine practice, or indirect nature of the evidence on health outcomes.

“C” recommends

The recommendation is based on expert opinion alone.

Among the most important, recommendations 61 to 64 address the extent of surgery in typical cases of MTC.

Recommendation 61

Patients with known or highly suspected MTC with no evidence of advanced local invasion by the primary tumor, no evidence cervical lymph node metastases on physical examination and cervical ultrasound, and no evidence of distant metastases should undergo total thyroidectomy and prophylactic central compartment (level VI) neck dissection (Grade B recommendation).

Prophylactic lateral neck dissection was omitted (Recommendation 61, Grade B). In discussion, the panel recognized a minority view that considers prophylactic ipsilateral modified neck dissection as a possible option. The data supporting this treatment recommendation are discussed later in further detail. Results of preoperative neck ultrasound and biopsy strongly influence the extent of surgery.

Recommendation 62

Patients who have MTC with suspected limited local metastatic disease to regional lymph nodes in the central compartment (with a normal ultrasound examination of the lateral neck compartments) in the setting of no distant (extracervical) metastases or limited distant metastases should typically undergo a total thyroidectomy and level VI compartmental dissection. A minority of the Task Force favored prophylactic lateral neck dissection when lymph node metastases were present in the adjacent paratracheal central compartment (Grade B recommendation).

Hence, the finding of positive central and negative lateral nodes typically would be treated with total thyroidectomy and level VI dissection only (Recommendation 62, Grade B).

There is some controversy as to the recommended extent of lymph node dissection in patients presenting with a palpable nodule diagnosed on fine needle aspiration (FNA) cytology to be MTC. In a recent report, more than 80% of patients referred with persistent or recurrent MTC were judged to have had an inadequate initial operation. More than 50% of patients have persistently elevated calcitonin levels after initial surgery for MTC. As noted earlier, standard surgical treatment for patients diagnosed with MTC is total thyroidectomy and central compartment lymph node dissection. Controversy exists as to the requirement for a unilateral lateral neck lymph node dissection or bilateral lateral neck lymph node dissection.

In general, for patients with familial or sporadic MTC with clinical evidence of regional metastatic disease, compartment-oriented neck dissection in a systematic fashion is advocated. In patients with familial MTC and an elevated basal calcitonin level or a thyroid nodule palpable on physical examination or visualized on ultrasonography, total thyroidectomy with central compartment lymphadenectomy and bilateral lateral neck dissection may be performed. In patients with presumed sporadic MTC, and importantly when the primary mass is large (> 2 cm) or when paratracheal nodes are involved, an ipsilateral lateral neck dissection on the side of the lesion may also be indicated. In patients with palpable cervical lymphadenopathy a bilateral lateral neck dissection may also be performed. This approach maximizes local regional tumor control while minimizing the need for reoperation. With improvement in preoperative imaging, specifically high sensitivity ultrasound, operation in the contralateral lateral neck may be performed when cytologically proven disease by FNA is documented.

Moley recently analyzed the distribution of nodal metastases in patients where MTC presented as a palpable thyroid mass. These data indicate a significant incidence of disease in the contralateral lateral neck when patients presented with palpable MTC. In patients with unilateral palpable primary tumors, there was a 47% incidence of positive contralateral nodes in Levels II, III, and IV. These authors recommend a bilateral modified neck dissection in patients with palpable MTC. If this can indeed be performed safely, bilateral neck dissection would seem to maximize local tumor control even further. This dissection is controversial as noted earlier in the ATA recommendations.

Recommendation 63

Patients who have MTC with suspected limited local metastatic disease to regional lymph nodes in the central and lateral neck compartments (with ultrasound-visible lymph node metastases in the lateral neck compartments) in the setting of no distant metastases or limited distant metastases should typically undergo a total thyroidectomy, central (level VI), and lateral neck (levels IIA, III, IV, V) dissection (Grade B recommendation).

Thus, the presence of abnormal central and lateral nodes typically would lead to total thyroidectomy with central compartment dissection, and lateral neck dissection involving levels IIa, III, IV, and V.

Recommendation 64

In the presence of distant metastatic disease, less aggressive neck surgery may be appropriate to preserve speech, swallowing, and parathyroid function while maintaining locoregional disease control to prevent central neck morbidity (Grade C recommendation).

Thus, less aggressive neck surgery may be appropriate in the setting of extensive metastatic disease (Recommendation 64, Grade C).

Technical details of central and modified neck dissection

The extent of central neck dissection includes all thyroid tissue and all nodal tissue from the hyoid bone superiorly to the innominate vessels inferiorly. Central nodal tissue on the anterior surface of the trachea is resected and the superior surface of the innominate vein behind the sternal notch is exposed. Fibrofatty tissue between the carotid sheaths and trachea is removed including the paratracheal nodes along the recurrent laryngeal nerves. This dissection is continued inferiorly on the right to the point at which the junction of the innominate artery and carotid is exposed and to a comparable level on the left behind the head of the clavicle. This systematic compartment oriented lymphadenectomy approach to the surgical management of medullary thyroid cancer has been shown to improve local-regional control and suggested to improve survival ( Fig. 1 ).

Intraoperative and schematic sketch following total thyroidectomy, central compartment lymph node dissection, and modified lateral neck dissection in a patient with MEN 2A.

Adapted from Fleming JB, Lee JE, Bouvet M, et al. Surgical strategy for the treatment of medullary thyroid carcinoma. Ann Surg 1999;230(5):697–707; with permission.

A lateral neck lymph node dissection involves removal of lymph nodes anterior and posterolateral to the jugular vein. Defined limits are the posterior belly of the digastric muscle superiorly, the spinal accessory nerve posterolaterally, and the thoracic inlet and clavicle inferiorly. The sternocleidomastoid muscle, jugular vein, carotid artery, and vagus nerve are preserved (see Fig. 1 ). If the jugular vein or sternocleidomastoid muscle are involved with tumor, these are resected as a part of the specimen. If a bilateral dissection is indicated and the jugular vein has been resected on one side, this is best done as a two-stage procedure. If flow in the jugular vein is interrupted on the contralateral side, severe facial edema will result.

There is also some controversy as to how the parathyroid glands should be managed in these patients. Total parathyroidectomy with parathyroid autotransplantation and parathyroid preservation procedures have both been advocated. A strong argument can be made in this disease that it may not be possible to perform an adequate nodal clearance unless at least the inferior parathyroid glands are removed. The parathyroid glands may also be devascularized during the course of the central lymph node dissection. Thus, Moley and colleagues advocate total parathyroidectomy with autotransplantation as a part of total thyroidectomy and central nodal clearance in MTC. Alternatively, an attempt may be made to preserve in situ the superior parathyroid glands (usually located just superior and posterior to the junction of the recurrent laryngeal nerve and inferior thyroid artery). As suggested earlier, the inferior parathyroids are usually inseparable from the central compartment lymph nodes and the thymic horn that extends from the lower pole of the thyroid gland. Thus, the inferior parathyroids should be identified when possible, confirmed histologically to avoid autografting a lymph node metastasis, and then autografted into either the sternocleidomastoid muscle in the neck (and marked with a clip to facilitate identification if hyperparathyroidism was to develop) or into the non-dominant forearm.

There are, of course, other management issues of importance to consider in the overall surgical management of patients with MTC including

• 1.
  

  Work-up preoperatively for pheochromocytoma

  
  
• 2.
  

  The surgical management of coexisting endocrinopathies in patients with multiple endocrine neoplasia (MEN) IIA AND MEN IIB

  
  
• 3.
  

  The timing and extent of surgery in patients carrying the RET proto-oncogene mutation.