Comparing the 7th and 8th editions of UICC/AJCC staging system for nasopharyngeal carcinoma in the IMRT era.

ABSTRACT

BACKGROUND: To compare the prognostic value of 7th and 8th editions of the Union for International Cancer Control/American Joint Committee on Cancer (UICC/AJCC) staging system for patients with nonmetastatic nasopharyngeal carcinoma (NPC) treated with intensity-modulated radiotherapy and simultaneous integrated boost- intensity-modulated radiation therapy (SIB-IMRT). METHODS: Patients with NPC (n = 300) who received SIB-IMRT were included. Survival by T-classification, N-classification, and stage group of each staging system was assessed. RESULTS: For T-classification, nonsignificant difference was observed between T1 and T3 and between T2 and T3 disease (P = 0.066 and 0.106, respectively) for overall survival (OS) in the 7th staging system, whereas all these differences were significant in the 8th staging system (all P < 0.05). The survival curves for disease-free survival (DFS) and locoregional recurrence-free survival (LRRFS) in both staging systems were similar, except for the comparison of T2 and T4 disease for LRRFS (P = 0.070 for 7th edition; P = 0.011 for 8th edition). For N-classification, significant differences were observed between N2 and N3 diseases after revision (P = 0.046 and P = 0.043 for OS and DFS, respectively). For staging system, no significant difference was observed between IVA and IVB of 7th edition. CONCLUSION: The 8th AJCC staging system appeared to have superior prognosis value in the SIB-IMRT era compared with the 7th edition.