Incidence of lymph node metastasis from early gastric cancer: Estimation with a large number of cases at two large centers

Background. The presence of lymph node metastasis (LNM) is the most important prognostic factor for patients with early gastric cancer (EGC). A D2 gastrectomy has been the gold standard treatment. Strict criteria for endoscopic mucosal resection have been widely accepted in Japan. There are some trials aimed at expanding the indications for local treatment, although there has not been a comprehensive review of the risk of LNM with the lesions of EGC. Methods. We investigated 5265 patients who had undergone gastrectomy with lymph node dissection for EGC at the National Cancer Center Hospital and the Cancer Institute Hospital. Nine clinicopathological factors were assessed for their possible association with LNM. Results. None of the 1230 well differentiated intramucosal cancers of less than 30 mm diameter regardless of ulceration findings, were associated with metastases (95% confidence interval [CI], 0-0.3%). None of the 929 lesions without ulceration were associated with nodal metastases (95% CI, 0-0.4%) regardless of tumor size. Similarly to findings for intramucosal cancers, for submucosal lesions, there was a significant correlation between tumor size larger than 30mm and lymphatic-vascular involvement with an increased risk of LNM. None of the 145 differentiated adenocarcinomas of less than 30-mm-diameter without lymphatic or venous permeation were associated with LNM, provided that the lesion had invaded less than 5001μm into the submucosa (95% CI, 0-2.5%). Conclusion. Based on our large series of cases, we have been able to clarify the risks associated with EGC and to propose expansion of the criteria for local treatment. However, accurate histological evaluation of the resected specimens is essential to avoid recurrence for such EGCs that should be cured.