Risk factors associated with lymph node metastasis in cN0 papillary thyroid microcarcinoma

Although active surveillance (AS) is increasingly recommended for low risk papillary thyroid microcarcinoma (PTMC), a subset of patients with clinically node-negative (cN0) disease actually harbor occult lymph node metastasis (LNM), which may lead to delayed surgical intervention and poorer outcomes. This study aimed to identify independent risk factors for LNM in cN0 PTMC patients to refine preoperative risk stratification and guide individualized treatment decisions.

We retrospectively analyzed 2097 cN0 PTMC patients who underwent thyroidectomy with central lymph node dissection at Tianjin Cancer Hospital Airport Hospital between September 2019 and March 2025. Preoperative clinical, ultrasonographic, and laboratory data were collected. Univariate and multivariate logistic regression analyses were performed to identify independent predictors of LNM. Receiver operating characteristic (ROC) curve analysis was used to evaluate predictive efficacy and determine optimal cut-off values.

Postoperative LNM was confirmed in 865 patients (41.2%). Multivariate analysis identified male sex (OR = 2.108, 95% CI: 1.632-2.723), younger age (OR = 0.964, 95% CI: 0.954-0.974), larger tumor diameter (OR = 4.001, 95% CI: 2.329-6.871), multifocality (OR = 1.300, 95% CI: 1.037-1.629), BRAF V600E mutation (OR = 8.938, 95% CI: 6.900-11.579), and higher neutrophil-to-lymphocyte ratio (NLR) (OR = 11.158, 95% CI: 8.221-15.138) as independent risk factors for LNM (all p < 0.05). ROC analysis revealed optimal cut-off values of ≤43.5 years for age, ≥0.65 cm for tumor diameter, and ≥1.925 for NLR. BRAF V600E mutation and NLR demonstrated the highest predictive efficacy (AUC = 0.720 and 0.759, respectively).

In cN0 PTMC patients, male sex, age ≤43.5 years, tumor diameter ≥0.65 cm, multifocality, BRAF V600E mutation, and NLR ≥1.925 are independently associated with increased risk of cervical LNM. Preoperative assessment of these factors enables refined risk stratification for patients being considered for AS, facilitating more precise and individualized surveillance strategies. These findings underscore the importance of integrating clinical, pathological, and molecular parameters in PTMC risk stratification. Future prospective studies are warranted to validate whether early surgical intervention confers superior survival benefits over continued AS in high risk subgroups.