Evaluation of the Seventh American Joint Committee on Cancer/International Union Against Cancer Classification of gastric adenocarcinoma in comparison with the sixth classification

Abstract

The seventh TNM staging system for gastric cancer of the American Joint Committee on Cancer/International Union Against Cancer (AJCC/UICC) had a more detailed classification than the sixth TNM staging system for both the tumor (T) and lymph nodes (N). The authors compared survival rates assessed by the seventh staging system with those by the sixth system. The authors analyzed the prospectively collected database on patients with gastric cancer who underwent surgery at Seoul National University Hospital between 1986 and 2006, and calculated the survival rates of 9998 cases with primary cancer, R0 resection, and >14 retrieved lymph nodes. The 5-year cumulative survival rates (5YSR) according to the seventh edition T or N classifications were significantly different. The 5YSR according to seventh edition of the TNM staging system were 95.1% (stage IA), 88.4% (stage IB), 84.0% (stage IIA), 71.7% (stage IIB), 58.4% (stage IIIA), 41.3% (stage IIIB), and 26.1% (stage IIIC), which were significantly different from each other. The 5YSR of the seventh edition T2 and T3 classifications had significant differences in patients with every N classification, and the 5YSR of seventh edition N1 and N2 classifications had significant differences in T2 patients, T3 patients, and T4 patients. Each stage in the sixth edition was divided into the seventh edition stage with different survival rates. In addition, the number of homogenous groupings in seventh edition TNM stages was increased from 1 to 2. The seventh system provided a more detailed classification of prognosis than the sixth system, especially between T2 and T3 tumors and N1 and N2 tumors, although further studies were found to be needed for the N3a and N3b classification.