title: Risk Factors for Central Lymph Node Metastasis in CN0 Papillary Thyroid Carcinoma: A Systematic Review and Meta-Analysis.
abstract: BACKGROUND
  Central lymph node metastasis (CLNM) is common in papillary thyroid carcinoma (PTC). Prophylactic central lymph node dissection (PCLND) for patients with clinically negative central compartment lymph nodes (CN0) remains controversial. The phrase "clinically negative" is used to indicate that patients exhibited no clinical evidence of CLNM by ultrasonography (US) or computerized tomography (CT) preoperatively. In this study, we analyze the risk factors for CLNM in CN0 patients.
  
  
  METHODS
  The PUBMED and SCIE databases were systematically searched for works published through January 31, 2015. All of the patients included in this study underwent thyroidectomy+PCLND. Revman 5.3 software was used to analyze the data.
  
  
  RESULTS
  Twenty studies and 9084 patients were included in this meta-analysis. The following variables were associated with an increased risk of CLNM in CN0 patients: age < 45 years (OR = 1.59, 95% CI = 1.42-1.78, p<0.00001), male sex (OR = 1.95, 95% CI = 1.63-2.32, p<0.00001), multifocality (OR = 1.43, 95% CI = 1.22-1.67, p<0.00001), tumor size > 2 cm for PTC patients (OR = 2.98, 95% CI 2.08-4.28, p<0.00001) or tumor size > 0.5 cm for papillary thyroid microcarcinoma (PTMC) patients (OR = 2.30, 95% CI = 1.71-3.09, p<0.00001), location of the primary tumor in the central area and low pole (OR = 1.86, 95% CI = 1.48-2.33, p<0.00001), lymphovascular invasion (OR = 4.35, 95% CI = 2.24-8.46, p<0.0001), extrathyroidal extension (OR = 2.27, 95% CI = 1.76-2.94, p<0.00001), and capsular invasion (OR = 1.72, 95% CI = 1.39-2.41, p<0.00001). PTC (tumor size > 1 cm) exhibited a higher risk factor associated with CLNM than PTMC (tumor size < 1 cm) (OR = 2.83, 95% CI = 2.15-3.72, p<0.00001). Bilateral tumors (OR = 1.21, 95% CI = 0.92-1.58, p = 0.17) and lymphocytic thyroiditis (OR = 0.88, 95% CI = 0.71-1.09, p = 0.25) had no association with CLNM in CN0 patients.
  
  
  CONCLUSIONS
  Our systematic review identified several clinical features associated with CLNM in CN0 patients, including age, sex, multifocality, size, location, lymphovascular invasion, capsular invasion, and extrathyroidal extension. These factors should guide the application of PCLND in CN0 patients.
authors.affiliation: Department of Thyroid Surgery, The First Hospital of China Medical University, Shenyang, Liaoning Province, China.
authors.forename: Wei
authors.initials: W
authors.lastname: Sun
authors.affiliation: Department of Thyroid Surgery, The First Hospital of China Medical University, Shenyang, Liaoning Province, China.
authors.forename: Xiabin
authors.initials: X
authors.lastname: Lan
authors.affiliation: Department of Thyroid Surgery, The First Hospital of China Medical University, Shenyang, Liaoning Province, China.
authors.forename: Hao
authors.initials: H
authors.lastname: Zhang
authors.affiliation: Department of Thyroid Surgery, The First Hospital of China Medical University, Shenyang, Liaoning Province, China.
authors.forename: Wenwu
authors.initials: W
authors.lastname: Dong
authors.affiliation: Department of Thyroid Surgery, The First Hospital of China Medical University, Shenyang, Liaoning Province, China.
authors.forename: Zhihong
authors.initials: Z
authors.lastname: Wang
authors.affiliation: Department of Thyroid Surgery, The First Hospital of China Medical University, Shenyang, Liaoning Province, China.
authors.forename: Liang
authors.initials: L
authors.lastname: He
authors.affiliation: Department of Thyroid Surgery, The First Hospital of China Medical University, Shenyang, Liaoning Province, China.
authors.forename: Ting
authors.initials: T
authors.lastname: Zhang
authors.affiliation: Department of Thyroid Surgery, The First Hospital of China Medical University, Shenyang, Liaoning Province, China.
authors.forename: Siming
authors.initials: S
authors.lastname: Liu
mesh_terms: D002277:Carcinoma / Q000473:pathology*; D002291:Carcinoma, Papillary; D006801:Humans; D008207:Lymphatic Metastasis; D012307:Risk Factors; D000077273:Thyroid Cancer, Papillary; D013964:Thyroid Neoplasms / Q000473:pathology*