Young Age and Male Sex Are Predictors of Large-Volume Central Neck Lymph Node Metastasis in Clinical N0 Papillary Thyroid Microcarcinomas

Background: Large-volume lymph node metastasis (LNM) is associated with poor clinical outcomes in papillary thyroid microcarcinoma (PTMC) patients. However, sensitivity in the detection of central neck LNM on preoperative neck ultrasonography (US) is believed to be low. The aim of this study is to investigate the preoperative clinical factors associated with large-volume LNM in clinical N0 PTMC patients. Methods: In all, 2329 clinical N0 PTMC patients who underwent total thyroidectomy with prophylactic central lymph node (LN) dissection were evaluated. The LNM status of these patients was divided into three groups by the number of metastatic nodes: no LNM, small-volume LNM (≤5 metastatic LNs), and large-volume LNM (>5 metastatic LNs). The correlations between age, sex, and other clinical factors and large-volume LNM were evaluated. Results: Large-volume LNM was found in 94 (4.0%) patients. Young (<40 years old) and male patients tended to have large-volume LNM (p for trend <0.001). Young age (odds ratio [OR] = 2.69 [confidence interval (CI) 1.64–4.32], p < 0.001) and male sex (OR = 5.79 [CI 3.67–9.10], p < 0.001) were independent risk factors for large-volume LNM in multivariate analyses. The prevalence of large-volume LNM ranged from 24% in male patients <40 years of age to only 2% in female patients aged ≥40 years. Multifocal tumors and presence of extrathyroidal extension were also considered risk factors for large-volume LNM. Conclusions: Large-volume LNM was more frequently found in young (<40 years) and male patients. These findings support the notion that surgery rather than observation may be favored in young and male clinically LN negative PTMC patients as a primary therapeutic option.