title: Significance of micrometastases in the calculation of the lymph node ratio for papillary thyroid cancer.
abstract: OBJECTIVE
  The lymph node ratio (LNR) is an important prognostic factor in papillary thyroid carcinoma (PTC), but micrometastases in cervical lymph nodes (LNs) are not of great clinical importance. In this study, we analyzed the accuracy of prediction of the prognosis depending on whether micrometastases were included in the number of metastatic LNs when calculating LNR.
  
  
  METHODS
  The study included 353 PTC patients who underwent total thyroidectomy with neck LN dissection, and calculated LNR by 2 methods according to whether micrometastases were included in the number of metastatic LNs: Method 1 did not and method 2 did include. To compare the predictive values of LNR by the 2 methods, correlation coefficients and receiver operating characteristic (ROC) curves were analyzed.
  
  
  RESULTS
  Positive correlations were found between LNR and preablation stimulated thyroglobulin (sTg) levels in both methods, but the correlation between method 1 LNR and preablation sTg level was significantly stronger than that for method 2 (Fisher z = 1.7, P = 0.045). The areas under these 2 independent ROC curves were analyzed; the prognostic efficacy of method 1 LNR was more accurate than that of method 2 LNR, and the difference was statistically significant (P = 0.0001).
  
  
  CONCLUSIONS
  Regional recurrence of PTC can be predicted more accurately by not including micrometastases in the number of metastatic LNs when calculating LNR.
authors.affiliation: Department of Breast Endocrine Surgery, Korea University College of Medicine, Seoul, Korea.
authors.forename: Young Woo
authors.initials: YW
authors.lastname: Chang
authors.affiliation: Department of Breast Endocrine Surgery, Korea University College of Medicine, Seoul, Korea.
authors.forename: Hwan Soo
authors.initials: HS
authors.lastname: Kim
authors.affiliation: Department of Breast Endocrine Surgery, Korea University College of Medicine, Seoul, Korea.
authors.forename: Seung Pil
authors.initials: SP
authors.lastname: Jung
authors.affiliation: Department of Breast Endocrine Surgery, Korea University College of Medicine, Seoul, Korea.
authors.forename: Hoon Yub
authors.initials: HY
authors.lastname: Kim
authors.affiliation: Department of Breast Endocrine Surgery, Korea University College of Medicine, Seoul, Korea.
authors.forename: Jae Bok
authors.initials: JB
authors.lastname: Lee
authors.affiliation: Department of Breast Endocrine Surgery, Korea University College of Medicine, Seoul, Korea.
authors.forename: Jeoung Won
authors.initials: JW
authors.lastname: Bae
authors.affiliation: Department of Breast Endocrine Surgery, Korea University College of Medicine, Seoul, Korea.
authors.forename: Gil Soo
authors.initials: GS
authors.lastname: Son
keywords: Lymph nodes; Papillary thyroid carcinoma