The Prognostic Significance of the Metastatic Lymph Node Ratio in Patients with Papillary Thyroid Carcinoma

Sang Yull Kang; Seon Kwang Kim; Hyun Jo Youn; Sung Hoo Jung

doi:10.16956/kjes.2015.15.3.67

Journal List > Korean J Endocr Surg > v.15(3) > 1060149

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Kang, Kim, Youn, and Jung: The Prognostic Significance of the Metastatic Lymph Node Ratio in Patients with Papillary Thyroid Carcinoma

Original Article

Korean Journal of Endocrine Surgery 2015; 15(3): 67-72.

Published online: 24 September 2015

DOI: https://doi.org/10.16956/kjes.2015.15.3.67

The Prognostic Significance of the Metastatic Lymph Node Ratio in Patients with Papillary Thyroid Carcinoma

Sang Yull Kang, Seon Kwang Kim, Hyun Jo Youn, Sung Hoo Jung

Division of Breast·Thyroid Surgery, Department of Surgery, Chonbuk National University Medical School, Jeonju, Korea.

Correspondence: Hyun Jo Youn. Division of Breast·Thyroid Surgery, Department of Surgery, Chonbuk National University Medical School, 20 Geonji-ro , Deokjin-gu, Jeonju 54907, Korea. Tel: +82-63-250-2389, Fax: +82-63-271-6197, yhj0903@jbnu.ac.kr

Received 29 June 2015 Revised 17 August 2015 Accepted 2 September 2015

(open-access):

This is an open-access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/by-nc/4.0/), which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

Purpose

Metastatic lymph node ratio (MLNR) is known as an important prognostic factor in many solid carcinomas; however, the role of MLNR in papillary thyroid carcinoma (PTC) is unclear. The purpose of this study was to determine whether MLNR has prognostic significance for recurrence in patients with pathological N1a PTC.

Methods

A retrospective analysis was conducted of 1,198 patients with PTC who underwent total thyroidectomy with central neck dissection between 2006 and 2011. Only patients with central lymph node metastasis were included in this study. Patients with lateral neck lymph node metastasis or extrathyroidal involvement were excluded. Finally, this study included 282 patients with N1a patients. MLNR was defined as the number of metastatic lymph nodes divided by the number of removed lymph nodes.

Results

Median age was 47.3 years (17~73 years). There were 209 female patients and 41 male patients, respectively. Median follow-up period was 53 months (36~114 months). Median value of MLNR was 0.36 (0.04~1.000). Of 250 patients, 20 patients (8.0%) developed recurrent disease. MLNR independently predicted PTC recurrence (odds ratio [OR], 6.385; 95% confidence interval [CI], 2.523-16.158; P < 0.001). In receiver operating characteristic curve analysis, 0.47 was significantly meaningful for recurrence when three or more lymph nodes were collected.

Conclusion

MLNR is an independent predictor of PTC recurrence in patients with pathological N1a PTC. Therefore, N1a patients with MLNR > 0.47 should be monitored closely for recurrence.

Keywords: Thyroid carcinoma, Lymph node, Ratio, Recurrence

Figures and Tables

Fig. 1

Description of study cohort. A total of 250 patients were enrolled in this study.

Fig. 2

Recurrence-free survival curves according to metastatic lymph node ration (MLNR) in patients with pN1a papillary thyroid carcinoma. There was a significant difference between patients with MLNR 0.47 and ≥ 0.47 (P<0.001).

Fig. 3

In tumor size ≤1 cm group and 1 cm <tumor size ≤2 cm group, there was a significant difference in recurrencefree survival in patients group according to metastatic lymph node ratio (MLNR) (P=0.044; P=0.004; respectively) (A, B). However, there was no difference in tumor size >2 cm group (P=0.386) (C).

Table 1

Patient clinicopathological characteristics

LN = lymph node; MLNR = metastatic lymph node ratio.

Table 2

Relationship between MLNR group and clinicopathological variables of patients

MLNR = metastatic lymph node ratio.

Table 3

Multivariate cox regression analysis of variables with recurrence

CI = confidence interval; NMLN = number of metastatic lymph node; MLNR = metastatic lymph node ratio.

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