Recommendation for subclass evaluation of TNM stage iva papillary thyroid carcinomas: T4aN1b patients are at risk for recurrence and survival.

Background: Although all tumor, node, metastasis system (TNM) stage IVA papillary thyroid carcinomas (PTCs) do not seem to behave equivalently as a result of various tumor and node stages, to our knowledge, subclass evaluation has never been attempted.

Methods: We reviewed 119 stage IVA PTC patients who underwent initial thyroidectomy with modified neck dissection as curative surgery at our institution (33 male patients, 86 female patients; age 61.6 years; follow-up 87.7 months). These patients were divided into groups A (T1-3N1b; n = 79), B (T4aN0-1a; n = 9), and C (T4aN1b; n = 31). Outcomes were compared between the groups.

Results: The rates of recurrence (P < .05) and disease mortality (P < .001) were 13.9% and 1.3%, 0% and 0%, and 35.5% and 19.4% in groups A, B, and C, respectively. The 10-year disease-free survival (DFS) and disease-specific survival (DSS) were 73.4% and 97.9%, 100% and 100%, and 54.9% and 69.7% in groups A, B, and C, respectively. DFS and DSS curves differed significantly between group A + B and group C (P < .005 and P < .0005, respectively). The relative risks of DFS and DSS in group C were 2.8-fold and 14.9-fold, respectively, compared with group A (P < .05), and 3.2-fold and 17.5-fold compared with group A + B (P < .01). Thus, outcomes were worse in group C. In multivariate analysis, esophageal invasion and lymphadenopathy were independent risk factors for both DFS and DSS in stage IVA PTC patients.

Conclusions: Outcomes in stage IVA are not equivalent, and patients with T4aN1b are at greater risk for worse prognosis. Therefore, we recommend subclass evaluation for TNM stage IVA PTCs.