Extent of cervical lymph node dissection: Recommendations from the Francophone Association for Endocrine Surgery, the French Society of Endocrinology and the French Society of Nuclear Medicine.

When metastatic ipsilateral central lymph nodes from thyroid cancer are identified pre- or intraoperatively (cN1a), ipsilateral central lymph node dissection should be performed concomitantly with thyroidectomy. When the patient is N1a on one side, contralateral prophylactic central lymph node dissection can also be considered. Prophylactic ipsilateral lymph dissection is not recommended. Ipsilateral compartment lymph node dissection is recommended in the corresponding sector for treatment of thyroid cancer with lymph node involvement (cN1b). Lymph node dissection can be limited to sectors III and IV when one of these sectors (or both) is involved and ultrasound does not demonstrate involvement of the other lateral sectors. Associated prophylactic lymph node dissection of sectors IIA and IIB is not recommended, while lymph node dissection of sector V (and exceptionally sector I) is indicated only when metastatic lymph nodes are proven. Prophylactic lymph node dissection of sector VB can be considered when positive lymph nodes are identified in sectors II, III and IV. When isolated metastatic lateral lymph nodes are identified (cN1b), prophylactic central (sector VI) lymph node dissection is recommended on the same side as the lateral compartment in addition to ipsilateral lateral lymph node compartment dissection. The level of evidence is insufficient to recommend prophylactic lateral lymph node dissection on the contralateral side for unilateral cN1b tumors. This type of lymph node dissection can be discussed for tumors that are at high risk of recurrence, bilateral tumors, in case of ipsilateral lateral lymph nodes > 3cm or in presence of > 4 metastatic lymph nodes in the central compartment.