Background: The aim of this study was to identify the risk factors for structural recurrence with a focus on lymph node-related factors and to determine the optimal cutoff size of lymph node micrometastases in patients with pathologic N1a classical papillary thyroid carcinoma.
Methods: We included patients who underwent total thyroidectomy with central compartment lymph node dissection for classic papillary thyroid carcinoma with pathologic N1a classification.
Results: A total of 398 patients were followed up for a median of 131 months. Structural recurrence occurred in 17.3% of patients (69/398). The multivariate analysis reported the following independent risk factors for structural recurrence: tumor size >1.95 cm, bilaterality, lymphatic and/or vascular invasion, a maximum diameter of the metastatic lymph node focus >3.5 mm, distribution of metastatic lymph node foci size >3.0 mm, and ≥4 metastatic lymph nodes.
Conclusion: The newly proposed cutoff of 3.5 mm for a definition of lymph node micrometastasis in pathologic N1a papillary thyroid carcinoma patients can reclassify the risk estimates of structural recurrence, thus modifying postoperative management plans and follow-up strategies.
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