Evaluating the influence of prophylactic central neck dissection on TNM staging and the recurrence risk stratification of cN0 differentiated thyroid carcinoma.

Objective: The purpose of this study was to explore the risk factors that were associated with central lymph node metastasis (CLNM) in patients with clinical nodal negative differentiated thyroid carcinoma (cN0 DTC) after prophylactic central neck dissection (pCND). The influence of pCND on TNM staging and recurrence risk stratification (RRS) in patients with cN0 DTC was also evaluated in our study.

Methods: A total of 153 cN0 DTC patients in Guangdong general hospital who underwent thyroidectomy with pCND from March 2014 to October 2014 were enrolled in this study. The relations of CLNM with clinicopathologic characteristics of cN0 DTC were analyzed by univariate and multivariate logistic regression. The influence of pCND on migration of TNM staging and RRS in cN0 DTC was observed.

Results: In the present study, CLNM was found in 42.5% (65 of 153 cases) of patients with cN0 DTC. On univariate analysis, the age less than 45 years old, tumor size more than 2cm, pT staging, and a total number of central lymph nodes dissected more than 3 were significantly associated with CLNM (P<0.05); however, gender, tumors affecting both lobes, multifocality, capsular invasion, and Hashimoto's thyroiditis were not related with CLNM (P>0.05). On multivariate logistic regression, age<45 years (P=0.001) and a total number of central lymph nodes dissected >3 (P=0.002) were significantly associated with CLNM. Because of the identification of CLNM in the implementation of pCND, 15 (9.8%) of 153 cN0 DTC patients were upgraded in TNM staging; all these patients were older than 45 years. Fifty-six patients (36.6%) developed higher RRS (from low to intermediate) after pCND.

Conclusions: For younger patients (age<45 years), careful preoperative assessment of the lymph node status must be done; surgeons should consider this risk factor when deciding whether to perform pCND. Thorough lymphadenectomy in the implementation of pCND can avoid residual lymph node metastasis and help to increase the incidence of CLNM. pCND can indentify occult CLNM which allows more precise TNM staging (for patients with age≥45 years) and RRS.