Clinically Significant Central Lymph Node Metastasis is Not Common in Patients with Clinically N0 Papillary Thyroid Carcinoma on Both Ultrasonography and CT.

The necessity of prophylactic central lymph node dissection (p-CLND) in patients with clinically node-negative papillary thyroid carcinoma (PTC) is unclear. The present study evaluated the central lymph node (LN) metastases status in patients with clinically node-negative PTC on both preoperative thyroid ultrasonography (USG) and neck computed tomography (CT) who underwent p-CLND. This retrospective cohort study included 3002 clinically node-negative patients diagnosed with PTC who had undergone thyroidectomy with p-CLND from January 2000 to September 2022. Clinically node-negative was defined as the absence of suspicious metastatic LNs on preoperative USG and neck CT. Low-risk central LN metastases were defined as LN metastases <2 mm in size with metastatic LNs ≤5. The median follow-up duration was 4.52 (interquartile range [IQR]: 1.6-7.5) years. Of the 3002 patients, 1194 (39.7%) had central LN metastases, whereas 1808 (60.3%) did not. The 1194 patients with central LN metastases included 507 (16.9%) with intermediate-risk metastases and 610 (20.3%) with low-risk LN metastases, with a total of 2428 (80.5%) patients having low-risk LN metastases or no central LN metastases. High-risk metastases were observed in only 77 (2.5%) patients. Of the 584 patients with intermediate-/high-risk metastases, 577 (98.8%) had central LN metastases <1 cm in size, whereas only 7 (1.2%) had central LN metastases ≥1 cm. The disease recurrence rates for the no LN metastases, low-risk LN metastases, and intermediate-/high-risk LN metastases groups were 0.4%, 1.1%, and 1.9%, respectively ( = 0.012). Factors independently associated with intermediate-/high-risk central LN metastases included age <55 years (odds ratio [OR] = 2.29), male sex (OR = 2.33), tumor size >1 cm on USG (OR = 1.94), and the presence of extrathyroidal extension on CT scans (OR = 1.53), with < 0.001 for all factors. Most LNs confirmed after CLND in cN0 PTC patients assessed by USG and CT were either metastasis-free or classified as low-risk metastatic LNs. Furthermore, the majority of metastatic LNs were small in size, typically measuring <1 cm. p-CLND may be unnecessary if preoperative thyroid USG and neck CT show no evidence of central neck LN metastaes.