Objective: The eighth edition of the American Joint Committee on Cancer (AJCC-v8) for anaplastic thyroid cancer (ATC) made a revision in staging for patients with lymph node metastasis (LNM) based on the seventh edition of AJCC (AJCC-v7). Our study aimed to evaluate the predictive ability of AJCC-v8 for survival in patients with ATC by exploring the association between lymph node stage and prognosis of ATC patients.
Methods: Retrospective study of ATC in Surveillance, Epidemiology and End Results (SEER) database. The association between LNM and survival of ATC was estimated by the Kaplan-Meier method and Cox regression model. The predictive performances of the AJCC-v8 and AJCC-v7 were estimated through C-index, Akaike information criterion (AIC) and Bayesian information criterion (BIC).
Results: A total of 313 patients with ATC were included in our analysis. Notably, LNM was identified as an independent risk factor for ATC mortality (adjusted HR, 1.47, 95% CI, 1.10-1.96; p = .009), while the risk of mortality in N1a group was comparable to that in N1b group according to univariate (HR, 1.30, 95% CI, 0.92-1.82; p = .133) and multivariate (adjusted HR 0.87, 95% CI, 0.60-1.27; p = .467) cox analyses. Applying the AJCC-v8, the survival of migration population staged T1-3aN1M0 was significantly worse than that of T1-3aN0M0 patients (IVA stage), while was not different from that of T3b-T4bN0/N1M0 patients (IVB stage). With a higher C-index (0.60 vs. 0.59), lower AIC (2728 vs. 2732) and BIC (2732 vs. 2735), AJCC-v8 was demonstrably a more favourable prediction model than AJCC-v7.
Conclusions: This study demonstrated that LNM was independently associated with poor prognosis of ATC, and AJCC-v8 with the modified staging of patients with LNM showed better survival predictive performance in ATC patients than AJCC-v7.
Keywords: AJCC; Survival; anaplastic thyroid cancer; lymph node metastasis.
© 2021 The Authors. Clinical Endocrinology published by John Wiley & Sons Ltd.