Clinical characteristics and risk analysis of lymph node metastasis in patients with cN0 differentiated thyroid carcinoma

To examine the clinical attributes and likelihood of lymph node metastasis (LNM) in patients with differentiated thyroid carcinoma classified as clinically lymph node-negative (cN0), with a minimum tumor diameter > 0.5 cm and maximum tumor diameter < 3.0 cm. Clinical data of 232 patients who underwent radical thyroidectomy and satisfied the inclusion and exclusion criteria were collected, and we found that average age of the LNM-positive group was younger than that of the LNM-negative group (40.9 ± 10.8 vs. 45.3 ± 11.8, P = 0.0031); sex distribution also showed a statistically significant difference, with male patients being more prone to LNM (P = 0.0436). Patients with positive LNM exhibited higher ultrasound thyroid imaging reporting and data system (TI-RADS) scores for thyroid nodules (p < 0.001). In terms of maximum tumor diameter and RET fusion, the LNM-positive group was higher in LNM-negative group (1.11 ± 0.832 cm vs. 0.808 ± 0.616 cm, P = 0.0034 and 16.3% vs. 2.7%, P = 0.0026), showing a statistically significant difference, The proportion of multifocal lesions was also higher in the LNM-positive group (26.8% vs. 20.2%). Patients in the LNM-positive group had higher levels of peripheral blood thyroid stimulating hormone (2.68 ± 2.88 μIU/L vs. 2.12 ± 2.07 μIU/L). Notably, statistically significant differences were observed between the LNM-positive and negative groups in terms of prothrombin time activity (PT%) (110 ± 13.0% vs. 107 ± 11.5%, P = 0.034) and white blood cell (WBC) count (6.11 ± 1.76 × 10^9/L vs. 6.59 ± 1.85 × 10^9/L, P = 0.0495), and further investigations revealed that BMI (R = 0.19) and blood urea nitrogen (R = 0.17) were positively correlated with PT%, whereas PT% was negatively correlated with peripheral blood T3 (R = - 0.17) and T4 (R = - 0.13) levels, which has not been reported in previous studies. We observed that for patients with cN0 differentiated thyroid cancer, we should also pay attention to the influence of factors such as gender, age, tumor diameter, RET fusion, and even PT and WBC on lymph node metastasis.