Endocrine Abstracts

Background: The 2015 ATA guidelines recommend total thyroidectomy with therapeutic central lymph node dissection (CND) for papillary thyroid carcinoma (PTC) patients with clinical central lymph node metastasis (CLNM). The purpose of this study is to verify that total thyroidectomy with therapeutic bilateral CND is necessary for all patients with unilateral cN1a PTC.

Methods: This study retrospectively reviewed 899 PTC patients who had total thyroidectomy with bilateral CND from January 2012 to June 2017. The patients were divided into two groups according to the pre-operative central lymph node (CLN) status: cN0, no suspected CLNM; cN1a, suspicious CLNM. We compared the clinicopathologic features of both groups.

Results: The mean age was younger in cN1a group (P=0.002). Post-operative complications did not differ between the two groups. Chronic lymphocytic thyroiditis was more common in cN1a patients. In multivariate analysis, cN1a patients were associated with the number of CLNM > 5 (OR=2.24, P=0.006) and the maximal size of CLNM ≥ 2 mm (OR=3.67, P<0.001) in final pathology. However, unilateral cN1a did not increase the risk of contralateral lobe or contralateral level VI involvement. Among cN1a patients, 33 out of 106 (31.1%) patients were both CLNM ≤ 5 and largest CLNM < 2 mm, implying lobectomy with CND could have been sufficient.

Conclusions: Most of cN1a patients belonged to the intermediate risk group of recurrence and needed total thyroidectomy. However, if carefully selected, lobectomy and unilateral CND can be safely performed in about 30% of patients. Pre-operative careful clinical examination, rigorous radiologic evaluation, and intra-operative frozen section are prerequisite for this approach.