Frozen section analysis of central lymph nodes in papillary thyroid cancer: the significance in determining the extent of surgery.

Background: The indolent feature of papillary thyroid cancer (PTC) has recently led to an increase in less aggressive treatment options instead of total thyroidectomy (TT). We aimed to investigate the clinical significance of elective central compartment neck dissection (CCND) with intraoperative frozen analyses of the central lymph nodes (LNs) to determine the surgical extent of unilateral clinically node-negative PTC. Methods: We retrospectively reviewed the medical records of 290 patients with unilateral clinically node-negative PTC who underwent surgery and performed frozen analyses of the central LNs from 2020 to 2021 using our own nodal criteria with cut-off size 5 mm. The patients were divided and investigated according to the surgical extent and the National Comprehensive Cancer Network (NCCN) guidelines; diagnostic accuracy of the frozen analyses was estimated. Results: TT was performed in 16.2% of patients. The TT group had more metastatic nodes with a larger size, higher LN ratio (LNR), and more extranodal extension. The analyses based on the NCCN guidelines showed similar findings, but more completion TT was required compared with our criteria. The sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) of the frozen analyses were 94.6%, 100%, 100%, and 96.1%, respectively. Conclusions: Elective CCND with intraoperative frozen analyses is a highly reliable procedure that detects occult nodal metastasis in unilateral node-negative PTC patients. Our nodal criteria yielded significant aggressive nodal characteristics in the TT group while yielding less TTs compared with the NCCN guidelines. The concept and clinical significance of small-volume nodal metastasis in PTC should be further investigated.