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

Abstract

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. 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. 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. 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.