Clinical Analysis of Risk Factors for Cervical Lymph Node Metastasis in Papillary Thyroid Microcarcinoma: A Retrospective Study of 3686 Patients

Purpose: To investigate the risk factors for cervical lymph node metastasis (LNM) in papillary thyroid microcarcinoma (PTMC). Patients and Methods: In total, 3686 patients with PTMC who underwent initial surgery in Shanghai Jiao Tong University affiliated Sixth People's Hospital from January 2010 to December 2019 were retrospectively analyzed. Univariate and multivariate analyses were conducted to identify risk factors associated with cervical LNM. Results: Male gender [odds ratio (OR) = 1.420, P < 0.001], age < 55 years (OR = 2.128, P < 0.001), tumor size >6.5 mm (OR = 2.112, P < 0.001), lymphovascular invasion (LVI) (OR =2.110, P = 0.016), multifocality (OR = 1.358, P = 0.022), extrathyroidal extension (ETE) (OR = 1.598, P < 0.001), and lateral LNM (LLNM) (OR = 6.383, P < 0.001) served as independent risk factors for central LNM (CLNM). Moreover, male gender (OR = 1.668, P = 0.001), tumor size >6.5 mm (OR = 2.223, P < 0.001), chronic lymphocytic thyroiditis (OR = 1.402, P = 0.021), LVI (OR = 4.582, P < 0.001), ETE (OR = 1.393, P=0.023), and CLNM (OR = 6.212, P < 0.001) served as independent risk factors for LLNM. Furthermore, solitary PTMC with lesions in the upper third of the thyroid gland were more associated with LLNM than lesions in the other regions. Conclusion: This study suggests that meticulous evaluation of risk factors associated with LNM is required in order to guide the surgical treatment of PTMC patients in clinical practice.