Cohort Study Based on the Seventh Edition of the TNM Classification for Gastric Cancer: Proposal of a New Staging System

Abstract

Purpose We investigated the effect of the new TNM classification on gastric cancer staging. Patients and Methods From hospital records, information from patients with gastric cancer, who had undergone either total or partial gastrectomy for adenocarcinomas of the stomach or esophagogastric junction, was retrieved. The pathologic TNM stage was determined according to the sixth and seventh editions of the International Union Against Cancer guidelines and was based on surgical pathologic examination. Results Five hundred fifty-four patients (338 men and 216 women; median age, 68 years) had undergone partial or complete gastrectomy for intestinal (n = 209) or diffuse (n = 249) adenocarcinoma of the esophagogastric junction and stomach. Survival data and date of death were available for all patients. Patient death correlated significantly with age at diagnosis, tumor type, histologic grade, local tumor growth (T category), number of metastatic lymph nodes, lymph node ratio, lymph node status (N category), and tumor stage. No major difference was noted between the sixth and seventh editions of the TNM classification. On the basis of survival data, we revised the stage grouping system; stage I and II tumors were confined to nonmetastatic tumors, and stage III and IV tumors were confined to metastatic tumors. The Kaplan-Meier plots of this modified stage grouping showed statistically significant differences between individual stage subgroups without crossing curves and demonstrated improved survival of patients with stage II disease. Conclusion The seventh edition of the TNM classification is associated with a stage migration in 60% of patients with esophagogastric and stomach cancer. This change did not improve the assessment of patient prognosis, and therefore, a revised staging system is proposed.