OBJECTIVETo study clinicopathologic factors related to central lymph node (CLN) metastasis in different subregions for unilateral papillary thyroid carcinoma (PTC) with clinical N0.

METHODSA total of 145 PTC cases with clinical N0 treated in the same group of the department of head and neck surgery, Cancer Hospital, Chinese Academy of Medical Science between Jan. 2011 and Jan. 2014 was analysed retrospectively. Clinicopathologic factors related to CLN metastasis in different subregions were analyzed, including sex, age, tumor size, extrathyroidal extension, and multifocal tumor.

RESULTSCLN metastases existed in 57.9% (84/145) cases and the incidences of ipsilateral paratracheal, pretracheal, and prelaryngeal metastasis were 53.8%, 24.1% and 11.3% respectively. Right paratracheal lymph node metastasis occurred in anterior (17/38, 44.7%) and posterior (12/38, 31.6%) to the recurrent laryngeal nerve. Multivariate analysis indicated that extrathyroidal extension (OR = 4.49, 95%CI 1.80-11.20, P = 0.001) and tumor size (OR = 2.17, 95%CI 1.06-4.45, P = 0.034) were independent risk factors for ipsilateral paratracheal CLN metastasis; ipsilateral paratracheal CLN metastasis (OR = 2.12, 95%CI 0.08-4.60, P = 0.003) was an independent risk factor for pretracheal CLN metastasis.

CONCLUSIONSA high risk of CLN metastasis especially ipsilateral paratracheal metastasis exists in DTC with clinical N0. Ipsilateral paratracheal, pretracheal and prelaryngeal CLN dissection should be conducted when maximum tumor diameter more than 1 cm or extrathyroidal extension. CLN anterior and posterior to the recurrent larygeal nerve should be removed simultaneously when the ipsilateral paratracheal CLN metastasis at right side. Total thyroidectomy and contralateral paratracheal CLN dissection should be conciderded in multifocal tumor.