Central Lymph Node Status has Significant Prognostic Value in the Clinically Node-Negative Tall-Cell Variant of Papillary Thyroid Cancer Regardless of T-Staging and Radioactive Iodine Administration: First Evidence From a Population-Based Study.

BACKGROUND: The prognostic value of central lymph node (CLN) status in papillary thyroid cancer (PTC) remains controversial. This study aimed to provide the first evidence on this issue for the aggressive tall-cell variant (TCV) subtype.

METHODS: The study identified TCV patients from the Surveillance, Epidemiology, and End Results database. The Kaplan-Meier method, log-rank test, and multivariate Cox regression models were used for analysis.

RESULTS: Of the 744 patients included, 404 were recorded as N0, which were pathologically or only clinically confirmed. Overall survival (OS) and cancer-specific survival (CSS) did not differ significantly between the N0 and pN1a patients (p > 0.05). To investigate the reason, the N0 patients were subdivided according to the number of examined lymph nodes (ELN). The patients with a N0 diagnosis confirmed by two or more ELNs (N0-e2+) showed significantly better outcomes than the pN1a patients and their N0 counterparts without ELN (N0-e0) (p < 0.05), whereas the N0-e0 and pN1a groups demonstrated comparable outcomes in both the log-rank and multivariate analyses (p > 0.05). Moreover, the subgroup analyses showed that even among the patients with early T-staging (T1-T2) or receipt of radioactive iodine (RAI) therapy, the N0-e0 patients still demonstrated compromised OS compared with the N0-e2+ group (p < 0.05).

CONCLUSION: The cN0 patients without ELN (N0-e0) had outcomes similar to those of the pN1a patients, but showed a poorer OS than the N0-e2+ group regardless of T-staging and RAI administration, suggesting that occult CLN metastases might act as a negative prognosticator in cN0 TCV. Therefore, prophylactic central neck dissection might be considered for biopsy-proven cN0 TCV patients. Prospective studies are expected to further validate our conclusions.