Metastatic Lymph Node Metastasis Has Predictive Values for Recurrence in Papillary Thyroid Carcinoma

Abstract

Objective: The authors aimed to evaluate the significance of absolute number of lymph node metastasis (LNM) in papillary thyroid microcarcinoma (PTMC) and the metastatic lymph node ratio (the ratio between metastatic lymph node and harvested lymph nodes; MLNR) in the central neck for the prediction of locoregional recurrence. Method: Through retrospective chart review between 2005 and 2009, 573 patients who underwent total thyroidectomy and central neck dissection and were followed-up more than 36 months were enrolled. Regarding the risk of recurrence, multivariate analyses were performed with the following variables: multiplicity of tumor, extrathyroidal extension, number of harvested lymph nodes. Results: Both the number of LNM and MLNR exhibited predictive significance toward locoregional recurrence ( P < .001). The lowest cutoff value of MLNR for a meaningful separation of disease recurrence was 0.44 (HR = 8.86, 95% CI = 1.49-52.58, P = .001) when 3 or more lymph nodes were harvested. Conclusion: Both the number of LNM and MLNR in the central neck have predictive values for loco-regional recurrence. When MLNR is higher than 0.44, there is an increased risk of locoregional recurrence with a HR of 8.86. These findings will supplement in further risk-stratification of locoregional recurrence.