Clin Exp Otorhinolaryngol.  2018 Mar;11(1):58-64. 10.21053/ceo.2017.00472.

Number of Metastatic Lymph Nodes and Ratio of Metastatic Lymph Nodes to Total Number of Retrieved Lymph Nodes Are Risk Factors for Recurrence in Patients With Clinically Node Negative Papillary Thyroid Carcinoma

• Zheng CM
• Ji YB
• Song CM
• Ge MH
• Tae K

• KMID: 2407794
• DOI: http://doi.org/10.21053/ceo.2017.00472

Abstract

OBJECTIVES
The number of metastatic lymph nodes (LNs) and the ratio between the number of metastatic LNs and the total number of retrieved LNs (the LN ratio [LNR]) have been proposed as risk factors for recurrence of papillary thyroid carcinoma (PTC). However, the significance of the number of LNs and the LNR in patients with clinically node negative PTC has not been clearly determined. The purpose of this study is to evaluate their significance.
METHODS
We retrospectively analyzed 382 patients with PTC who had undergone total thyroidectomy with prophylactic central neck dissection (CND) between January 2000 and December 2010. We excluded patients with lobectomy, concurrent lateral compartment neck dissection, a follow-up period less than at least 2 years, number of harvested central LNs less than or equal to one, clinically positive LN, distant metastasis, recurrent cancer or other types of malignancy. The correlations between recurrence and various clinicopathologic characteristics including tumor size, extrathyroidal extension (ETE), stage, number of metastatic central LNs, and the LNR were investigated.
RESULTS
After a mean follow-up period of 82.2±26.4 months, recurrence occurred in 14 patients (3.7%). Tumor size ≥20 mm, maximal ETE, presence of central LN metastasis, number of metastatic LNs ≥2, and LNR ≥0.31 correlated with recurrence in the univariate analysis. However, tumor size ≥20 mm, maximal ETE, number of metastatic LNs ≥2, and LNR ≥0.31 were significantly associated with recurrence in the multivariate analysis (hazard ratio=6.61, 7.17, 3.43, and 11.23, respectively).
CONCLUSION
The LNR and the number of metastatic LNs are independent prognostic risk factors for recurrence in patients with clinically node negative PTC, and these factors can be used to guide postoperative adjuvant therapy and follow-up strategy after prophylactic CND.

Keyword

Lymph Node Metastasis; Papillary Thyroid Cancer; Recurrence; Lymph Node Ratio; Central Neck Dissection

MeSH Terms

Follow-Up Studies
Humans
Lymph Nodes*
Multivariate Analysis
Neck Dissection
Neoplasm Metastasis
Recurrence*
Retrospective Studies
Risk Factors*
Thyroid Gland*
Thyroid Neoplasms*
Thyroidectomy

Figure

• 

  Fig. 1. Receiver operating characteristic curve for recurrence of papillary thyroid cancer. (A) Number of metastatic lymph nodes (LNs), (B) LN ratio of metastatic LNs to the total number of recovered LNs in the central compartment.

• 

  Fig. 2. Kaplan-Meier plot showing recurrence-free survival by (A) tumor size ≥20 mm, (B) maximal extrathyroidal extension, (C) number of metastatic lymph nodes ≥2, and (D) central lymph node ratio ≥0.31.

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