Risk Factors for Nodal Metastasis in cN0 Papillary Thyroid Microcarcinoma.

Background: Despite the majority of papillary thyroid microcarcinoma (PTMC) patients having an excellent prognosis, cervical lymph node metastases are common. The purpose of this study was to investigate the incidence and the predictive risk factors for occult central compartment lymph node metastasis (CLNM) in PTMC patients.

Methods: 178 patients with clinically node-negative (cN0) PTMC undergoing prophylactic central compartment neck dissection in our hospital from January 2008 to Jun 2010 were enrolled. The relationship between CLNM and the clinical and pathological factors such as gender, age, tumor size, tumor number, tumor location, extracapsular spread (ECS), and coexistance of chronic lymphocytic thyroiditis was analyzed.

Results: Occult CLNM was observed in 41% (73/178) of PTMC patients. Multivariate analysis showed that male gender, tumor size (≥6mm) and ECS were independent variables predictive of CLNM in PTMC patients.

Conclusions: Male gender, tumor size (≥6mm) and ECS were risk factors of CLNM. We recommend a prophylactic central lymph node dissection (CLND) should be considered in PTMC patients with such risk factors.