Effects of age range on the number of metastatic lymph nodes in papillary thyroid microcarcinoma

Purpose: Whether clinicopathologic risk factors are associated with the number of metastatic lymph nodes remains unclear. Thus, this study aimed to investigate the effects of age range on the number of metastatic lymph nodes in papillary thyroid microcarcinoma (PTMC). Methods: A series of 1115 patients with PTMC who underwent total thyroidectomy plus central lymph node dissection were analyzed. The clinical correlation between the number of metastatic lymph nodes and age range was retrospectively studied after adjusting for potential confounders. Results: Lymph node metastases were found more frequently in the age <45 group than in the age >= 45 group (P<0.001). Univariate regression analysis showed that age was significantly correlated with the number of metastatic lymph nodes (odds ratio -0.6, 95% confidence interval -0.8 to -0.4, P<0.001). After multivariable risk adjustment for potential confounding factors, age, subtype, extrathyroid extension, infiltration, and maximum tumor size remained positively associated with the number of metastatic lymph nodes. A linear relationship between age and the number of metastatic lymph nodes was observed: when below the turning point (56 years), the number of metastatic lymph nodes decreasing with the increasing age. Conclusions: Our findings suggest that age is associated with the number of metastatic lymph nodes in PTMC. Radical treatment may be necessary for younger PTMC patients.