A Comparison of Ho's, Fourth-edition, and Fifth-edition American Joint Committee Staging Systems for Nasopharyngeal Carcinoma

Pyo, Kyung Bo; Lee, Han Kook; Lee, Hwan Ho; Ahn, Kyung Mo; Lee, Bong Hee

Abstract

BACKGROUND AND OBJECTIVES: The incidence of nasopharyngeal carcinoma (NPC) is reported to be high in South China and Hong-Kong. For that reason, the Ho's staging system has been used in the Hong-Kong area, while the American Joint Committee on Cancer (AJCC) staging system has been commonly used in western countries. The fifth-edition staging system defines new rules for classifying NPC. The purpose of this study was to find out whether the fifth-edition of the AJCC staging system is better than Ho's and the fourth-edition AJCC staging system in predicting the prognosis of NPC. MATERIALS AND METHOD: Fifty NPC patients of World Health Organization type II and type III were restaged according to the Ho's staging system, the fourth-edition AJCC and the fifth-edition AJCC staging systems. The disease specific survival rate was calculated by T category, N category and stage grouping for each staging system.
RESULTS
The fifth-edition of AJCC showed good distribution compared with other systems in stage classification and also showed statistical significance in the disease specific survival rate between early carcinoma (stage I-II) and advanced carcinoma (stage III-IV). On the survival curve of T and N categories, the fifth-edition of AJCC showed statistical significance in the disease specific survival rate between T1-2 and T3-4 group, and also between N0-1 and N2-3 group. But Ho's staging system showed similar statistical results to the fifth-edition of AJCC, except for higher concentration of patients at stage III. The fourth-edition of AJCC didn't show any statistical significance among categories of T, N and the stage groups.
CONCLUSION
In considering the poorer survival rates resulting from the cranial nerve or intracranial invasion and bilateral, or lower neck lymph node metastasis, the extensive invasion to adjacent regions and lymph node metastasis may have an influence on the prognosis. As far as prognostic categories are concerned, the fifth-edition of AJCC appears to be an improvement over other system. So, we concluded that the fifth-edition of AJCC staging system is better than the fourth-edition of AJCC and Ho's staging system to predict the prognosis of NPC.