Clinical predictors of lymph node metastasis and survival rate in papillary thyroid microcarcinoma: analysis of 3607 patients at a single institution

Abstract

Background: The treatment of papillary thyroid microcarcinoma (PTMC) patients is controversial, as PTMC is often found incidentally and its prognosis is quite good. Because lymph node metastasis (LNM) is one of the main predictors of recurrence and impacts the survival rate of PTMC patients, this study aims to retrospectively identify the clinical factors that increase the risk of LNM and/or recurrence and can then be used to separate clinically unfavorable PTMCs from the rest and to help guide their treatment accordingly.

Methods: Clinical and pathologic data were collected from 3607 patients diagnosed with PTMC at Shanghai Renji Hospital between 2005 and 2015. Univariate and multivariate analyses were performed to identify the clinical predictors of LNM and survival rates were calculated by using the Kaplan-Meier method.

Results: Our univariate and multivariate analyses show that age of <45 y (P < 0.01), gender of male (P < 0.01), tumor diameter >0.7 cm (P < 0.01), and multifocality (P < 0.01) significantly increase the risk of central LNM. However, clinical factors, such as LNM, age, gender, multifocality, and operation range, do not affect the 10-y disease-free survival rate (P > 0.05).

Conclusions: Clinical factors, such as gender of male, age of <45 y, multifocality, and tumor size >0.7 cm, suggest a higher risk of LNM; however, they do not affect PTMC patients' 10-y disease-free survival rate. We recommend ipsilateral lobectomy to PTMC patients. For PTMC patients with higher LNM risk, preoperative central and lateral cervical lymph node imaging examination should be emphasized, and lymph node dissection is recommended. The range of dissection should be determined based on the imaging results.

Keywords: Lymph node metastases; Microcarcinoma; Papillary carcinoma; Survival rate; Thyroid.