Despite the excellent overall prognosis for patients with papillary thyroid microcarcinoma (PTMC), the rate of central lymph node (CLN) metastasis has been reported to be as great as 60% and the optimal surgical extent of PTMC has been controversial. The aim of this study is to identify factors for predict CLN metastasis in patients with PTMC.

We conducted a retrospective study of 535 patients with PTMC who underwent total thyroidectomy with prophylactic CLN dissection between Jan. 2008 and Aug. 2011. We analyzed the association of CLN metastasis and clinicopathologic characteristics.

CLN metastasis was found in 181 patients (33.8%). Results of univariate analysis showed an association of younger than 45 years of age, male gender, a tumor size greater than 5 mm, bilaterality, multiplicity, extrathyroidal extension, and positivity of resection margin with CLN metastasis. Of these, results of multivariate analysis showed that age (P=0.003), gender (P=0.004), tumor size (P<0.001), extrathyroidal extension (P=0.001), and status of resection margin (P=0.002) were independent predictive factors for CLN metastasis.

A large tumor size (>5 mm), male gender, young age (<45 yr), extrathyroidal extension, and positive resection margin were determined as the predictive factors for CLN metastasis, which occurred in approximately one third of patients with PTMC. Therefore, prophylactic CLN dissectionshould be considered in patients with PTMC who have these factors through investigation before surgery.