Objectives: The 8th edition of the American Joint Committee on Cancer (AJCC) staging system for nasopharyngeal carcinoma (NPC) merged T4N0-2 and T1-4N3 to create stage IVa. In the present study, we aimed to assess the difference in clinical outcomes and patterns of failure between 8th AJCC T4N0-2 and T1-4N3 NPC patients treated with intensity-modulated radiotherapy (IMRT).
Methods: We included 3107 patients with stage IVa NPC disease (1871 with T4N0-2 and 1236 with T1-4N3) according to the 8th AJCC staging system. Overall survival (OS) was the primary endpoint. The clinical outcomes between T4N0-2 and T1-4N3 patients were compared.
Results: T1-4N3 patients had significantly worse 3-year OS (84.1% vs. 89.2%; p < 0.001) and distant metastasis-free survival (DMFS; 78.3% vs. 85.9%; p < 0.001), but better local relapse-free survival (LRFS; 94.9% vs. 92.2%; p = 0.003), as compared with T4N0-2 patients. Multivariate analysis showed that T1-4N3 was still an independent adverse prognostic factor for both DMFS (hazard ratio [HR] = 1.517, 95% confidence interval [CI] = 1.274-1.806, p < 0.001) and OS (HR = 1.315, 95% CI = 1.100-1.572, p = 0.003), whereas T4N0-2 was an independent adverse prognostic factor for LRFS (HR = 1.581, 95% CI = 1.158-2.158, p = 0.004).
Conclusions: In terms of the OS, T4N0-2 patients had better prognosis compared with T1-4N3 patients, and the patterns of failure differed between T4N0-2 and T1-4N3 patients. We believe that future modifications of the AJCC/UICC staging system should separate T4N0-2 from T1-4N3.
Key points: • In nasopharyngeal carcinoma, T4N0-2 patients tended to develop local relapse, whereas T1-4N3 patients were more likely to develop distant metastasis. • In terms of overall survival, T4N0-2 patients had better prognosis than T1-4N3 patients. • T4N0-2 should be separated from T1-4N3 in the UICC/AJCC staging system.
Keywords: Intensity-modulated radiotherapy; Nasopharyngeal carcinoma; Prognosis; Stage; Treatment failure.