Risk factors for cervical lymph node metastasis in papillary thyroid microcarcinoma: a study of 1,587 patients

The purposes of this study were to identify risk factors for cervical lymph node metastasis and to examine the association between BRAF^V600E status and clinical features in papillary thyroid microcarcinoma (PTMC).

A total of 1,587 patients with PTMC, treated in Tianjin Medical University Cancer Institute and Hospital from January 2011 to March 2013, underwent retrospective analysis. We reviewed and analyzed factors including clinical results, pathology records, ultrasound results, and BRAF^V600E status.

Multivariate logistic regression analyses demonstrated that gender (male) [odds ratio (OR) = 1.845, P = 0.000], age (< 45 years)(OR = 1.606, P = 0.000), tumor size (> 6 mm) (OR = 2.137, P = 0.000), bilateralism (OR = 2.011, P = 0.000) and extrathyroidal extension (OR = 1.555, P = 0.001) served as independent predictors of central lymph node metastasis (CLNM). Moreover, CLNM (OR = 29.354, P = 0.000) served as an independent predictor of lateral lymph node metastasis (LLNM). Among patients with a solitary primary tumor, those with tumor location in the lower third of the thyroid lobe or the isthmus were more likely to experience CLNM (P < 0.05). Univariate analyses indicated that CLNM, LLNM, extrathyroidal extension, and multifocality were not significantly associated with BRAF^V600E mutation.

The present study suggested that prophylactic neck dissection of the central compartment should be considered in patients with PTMC, particularly in men with tumor size greater than 6 mm, age less than 45 years, extrathyroidal extension, and tumor bilaterality. Among patients with PTMC, BRAF^V600E mutation is not significantly associated with prognostic factors. For a better understanding of surgical management of PTMC and the risk factors, we recommend multicenter research and long-term follow-up.