A Comparison Between the Chinese 2008 and the 7th Edition AJCC Staging Systems for Nasopharyngeal Carcinoma

Abstract

The Chinese 1992 staging system for nasopharyngeal carcinoma (NPC) was revised in 2008 and was renamed as the Chinese 2008 staging system. The seventh edition of the American Joint Committee on Cancer (AJCC) staging manual also defined new rules for classifying NPC in 2010. The purpose of the current study is to compare the 2 in terms of patient distribution and efficacy in predicting prognosis. A total of 816 patients with untreated nondisseminated NPC who underwent magnetic resonance imaging scan of the nasopharynx and neck were studied retrospectively. All magnetic resonance imaging scans were reevaluated independently by 2 radiologists specialized in head and neck cancers. All patients were restaged according to the Chinese 2008 staging system and the AJCC staging system of NPC. Using the 2 staging systems, the consistency for patient distributions in T, N, and overall stages was found to be moderate, with the κ value of 0.65, 0.54, and 0.46, respectively. According to the Chinese 2008 and the AJCC staging systems, the proportion of patients in stages I, II, III, and IV accounted for 2.3% versus 2.3%, 11.0% versus 23.7%, 39.4% versus 49.1%, and 47.3% versus 24.9%, respectively. The AJCC T classification was better in predicting the 5-year local relapse-free survival, whereas the Chinese 2008 N classification was superior in predicting the 5-year distant metastasis-free survival. However, survival curves for the 5-year overall survival were comparable in both systems. We revealed a slightly better patient distribution of overall stage with AJCC comparing with the Chinese 2008 staging system. The prognostic value of AJCC T classification was considered to be better, whereas that of Chinese 2008 N classification was superior.