Clinical Implication of the Number of Central Lymph Node Metastasis in Papillary Thyroid Carcinoma: Preliminary Report

Papillary thyroid cancer (PTC) metastasizes to central lymph node (CLN). CLN metastasis is associated with high risk of locoregional recurrence and distant metastasis. The significance of the number of metastatic CLN has not been addressed. This study was designed to evaluate the clinical implication of the number of metastatic CLN in PTC. We reviewed the patients who underwent total thyroidectomy and CLN dissection with or without lateral neck dissection due to PTC, from March 2008 to June 2009. The relationships between the number of CLN and risk factors, including age, gender, tumor size, extrathyroidal extension, and lateral lymph node metastasis, were assessed. Patients were divided into three groups according to the number of CLN: group A = 0; group B = 1-2; and group C = a parts per thousand yen3. Of 258 patients enrolled in this study, 113 were in group A, 73 in group B, and 72 in group C. Extrathyroidal extension and lateral neck lymph node metastasis were related to increased rate of CLN metastasis (P < 0.05). Tumor size increased as the number of CLN increased; group C had the largest tumor size (P < 0.05). When evaluating the distribution of patients with extrathyroidal extension, group C had a significant odds ratio (4.213, P < 0.05). When evaluating the distribution of lateral neck lymph node metastasis, groups B and C had significant odds ratio (14.353, 75.403, respectively, P < 0.05). The number of CLN metastasis correlated with the negative prognostic factors, including tumor size, extrathyroidal extension, and lateral neck lymph node metastasis. This suggests that the number of CLN has prognostic implication.