Patterns, Predictive Factors, and Prognostic Impact of Contralateral Lateral Lymph Node Metastasis in N1b Papillary Thyroid Carcinoma

Background Although the incidence among patients with bilateral lateral lymph node metastasis (LLNM) in N1b papillary thyroid carcinoma (PTC) is reported to be as high as 40%, only a few reports have addressed the characteristics of contralateral LLNM. Therefore, this study aimed to investigate the characteristics of patients with contralateral LLNM in N1b PTC. Methods This study retrospectively reviewed 834 patients with N1b PTC who underwent modified radical neck dissection between January 1997 and June 2015. Results Of the 834 N1b PTC patients, unilateral LLNM was found in 728 patients (87.3%) and bilateral LLNM in 106 patients (12.7%). The independent predictors of contralateral LLNM in N1b PTC patients were male sex (adjusted odds ratio [OR], 1.647; p = 0.039), tumor larger than 4 cm (adjusted OR, 6.700; p