Level VII is an Important Component of Central Neck Dissection for Papillary Thyroid Cancer

Abstract

Therapeutic central neck dissection (CND) is an accepted part of the management of papillary thyroid carcinoma (PTC), while prophylactic CND remains controversial. Regardless of the indication for CND, the lower anatomic border of the central compartment, specifically the inclusion or otherwise of level VII, is not always clearly defined in the literature. This study aimed to determine if the routine inclusion of level VII lymph node dissection as part of CND confers increased utility in the detection of macrometastatic lymph nodes compared with level VI dissection alone. This was a prospective cohort study of patients undergoing CND for PTC at a tertiary referral center. All patients received either a prophylactic or therapeutic CND. The CND specimens were divided by the surgeon into level VI and level VII at the level of the suprasternal notch and submitted separately for histopathology. Criteria for macroscopic lymph node disease were taken from the American Joint Committee on Cancer (AJCC) recommendations for breast cancer. A total of 45 patients with PTC underwent total thyroidectomy and routine CND, at a tertiary referral center; 77 % of the therapeutic CND group had positive level VI lymph nodes, and 38 % had positive level VII lymph nodes. Of the prophylactic CND group, 50 % of patients had positive level VI nodes and 16 % has positive level VII nodes detected. All patients with positive level VII lymph nodes in the prophylactic CND group had macrometastatic disease. Temporary hypocalcemia rate was 31 % in the therapeutic group and 6 % in the prophylactic CND group. One patient experienced permanent hypoparathyroidism. There was no vascular injury or recurrent laryngeal nerve palsy in either group. CND incorporating both level VI and level VII can be undertaken safely through a cervical incision with no increased risk of permanent complications of hypoparathyroidism or recurrent laryngeal nerve injury. Failure to include level VII as part of CND will leave significant macrometastatic nodal disease behind in both therapeutic and prophylactic dissections. As level VII is in direct anatomic continuity with the pretracheal level VI nodes, it should be routinely included as part of every CND.