Purpose: This study was carried out to propose a new staging system to improve the current UICC/AJCC staging system.
Methods: A total of 4217 patients who had undergone gastrectomy for gastric cancer from 1987 to 1997 were retrospectively reviewed. Among them, 4040 patients with either early gastric cancer (EGC, n=1202) or advanced gastric cancer (AGC, n=2838) can be appropriately staged by the 6th UICC/AJCC system. Survival rates of EGC were analyzed according to the number of lymph node metastasis while those of AGC patients were analyzed according to the TNM classifications.
Results: The 5-year survival rate (5-YSR) of EGC patients according to the 6th UICC/AJCC was 94.6% for stage Ⅰa, 92.9% for stage Ⅰb, and 40.9% for stage Ⅱ or Ⅳ. The 5-YSR according to the number of lymph node metastases in EGC patients was 94.6% for EGC patients with node negative, 95.1% for those with 1 or 2 positive nodes, and 73.4% for those with 3 or more positive nodes. The 95% confidence intervals of mean survival duration were narrower when patients were grouped with a reference number of metastatic lymph nodes as 3 than when patients were grouped according to the 6th UICC/AJCC staging system. The 5-YSR according to TNM classifications in AGC patients wss 89.8% for T2N0M0, 71.5% for T2N1M0, 74.9% for T3N0M0, 55.2% for T2N2M0, 58.6% for T3N1M0, 44.4% for T4N0M0, 35.1% for T3N2M0, 32.3% for T4N1M0, 9.4% for T4N2M0, 14.1% for TanyN3M0, and 7.6% for TanyNanyM1 The survival of T4N1M0 was rather similar to that of T3N2M0 (P=0.9225) than other TNM classifications in stage Ⅳ (P<0.0001).
Conclusion: With these results we may propose following new staging proposal. For EGC patients, the following division of N1 into two groups is recommanded: 1 or 2 positive lymph nodes as N1a and 3 or more positive nodes as N1b is recommended. With the new nodal classification in EGC, the staging recommendation for EGC patients is Ⅰ for T1N0M0 and T1N1aM0, and Ⅱ for T1N1bM0. For AGC patients, the following redistribution of TNM classification is recommanded for a new staging system, regarding T2N0M0 as stage Ⅰ and T4N1M0 as stage Ⅲb. In this new staging system, we can reduce the 6 stage groups into 5.
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