Is the 1997 AJCC staging system for nasopharyngeal carcinoma prognostically useful for Chinese patient populations?

Abstract 

The 5th edition of the American Joint Committee on Cancer (AJCC) staging manual defines new rules for classifying nasopharyngeal carcinoma (NPC). The study was conducted to assess its effectiveness in predicting the prognosis for Chinese patient populations.

Between June 1993 and June 1994, 621 consecutively admitted patients with nondisseminated NPC were treated with definitive-intent radiation therapy alone. All had computed tomography of the nasopharynx, skull base, and the upper neck. A computer database containing all information for staging was formed on presentation. The extent of disease of each patient was restaged according to the 1997 AJCC system.

Of the 621 patients, The 5-year overall survival (OS) rate was 60%. The 1997 AJCC system creates subgroups (Stages I to IV) that are assigned to 38 (6.1%), 270 (43.5%), 157 (25.3%), and 156 (25.1%) patients, respectively. The incidence of parapharyngeal extension was 74.1% (460/621). Of these patients (460) with parapharyngeal extension, 310 (67.4%) patients were classified as T2b disease. The 1997 AJCC system showed highly significant differences between the overall stages for both OS and relapse-free survival (RFS). The 1997 AJCC T classifications showed significant correlation with local failure, and N classification was accurate in predicting FDM. Multivariate analysis showed that paraoropharyngeal involvement was an independently significant prognostic factor for OS, freedom from local recurrence (FLR), and freedom form distant metastasis (FDM).

The 1997 AJCC staging system for NPC is prognostically useful for Chinese patient populations. We proposed that subdivision of parapharyngeal extension should be included in future revisions of the staging system.

Keywords:  American Joint Committee on Cancer, Nasopharyngeal carcinoma, Tumor staging, Prognosis