LAUSR

OBJECTIVE The first aim of this study was to explore the risk factors that were associated with central lymph node metastasis (CLNM) in patients with clinically node-negative papillary thyroid microcarcinoma (cN0 PTMC) after prophylactic central neck dissection (PCND). The second aim was to evaluate the influence of PCND on migration of TNM staging and risk stratification (RS) in patients with cN0 PTMC. METHODS A total of 295 cN0 PTMC patients who underwent thyroidectomy with PCND in the Department of General Surgery at Guangdong General Hospital between March 2014 to December 2015 were assessed retrospectively. The relations of CLNM with clinicopathologic characteristics of cN0 PTMC were analyzed by univariate and multivariate logistic regression. The effect of PCND on migration of TNM staging and RS was also observed. RESULTS The incidence of CLNM was 42.4% (125 of 295 cases) in patients with cN0 PTMC. Univariate analysis showed that age (P=0.000), ultrasonographic tumor size (P=0.009), pathologic tumor size (P=0.005), and multifocality (P=0.031) were significantly associated with the incidence of CLNM. No significant correlations were found between the presence of CLNM and other variables such as gender (P=0.399), bilaterality (P=0.118), capsular invasion (P=0.111), lymphovascular invasion (P=0.184), extent of thyroidectomy (P=0.319) and lymphadenectomy (P=0.458). Multivariate logistic regression analysis revealed that age <45 years (P=0.000) and multifocality (P=0.033) were independent predictors of CLNM in patients with cN0 PTMC. Because of the identification of CLNM in the implementation of PCND, 42 (14.2%) patients were upstaged, and 118 (40.0%) patients upgraded in RS. CONCLUSIONS CLNM is highly prevalent in cN0 PTMC. Age <45 years and multifocality are independent risk factors of CLNM in cN0 PTMC patients. PCND can identify CLNM, which allows more accurate TNM staging/RS and may have an important impact on postoperative treatment in cN0 PTMC patients.