Background and Objectives: Although various types of minimally invasive treatment have emerged as the best front-line therapies for early gastric cancer (EGC), there have been no established indications that these attempts are applicable. The purpose of this study was to propose indications for the application of minimally invasive therapy for EGC. Methods: A total of 566 patients with EGC who had undergone gastrectomy with D2 or more extended lymphadenectomy, from July 1993 to December 1997 were retrospectively analyzed. The risk factors that determine lymph node metastasis were investigated by univariate and multivariate analysis. Results: The rate of lymph node metastasis was 11.8% for all EGC, 3.4% for mucosal cancer, and 21.0% for submucosal cancer. Lymph node metastasis was associated with submucosal invasion, larger tumor size, undifferentiated histology, and the presence of lymphatic or blood vessel invasion (LBVI) by univariate and multivariate analyses. When LBVI was absent, there was no lymph node metastasis if the tumor was smaller than 2.5 cm with differentiated histology, and smaller than 1.5 cm with undifferentiated histology, regardless of depth of invasion. Extra-perigastric lymph node metastases were noted in patients with submucosal tumors that have LBVI while none of mucosal cancer showed extra-perigastric lymph node metastases. Conclusions: Minimally invasive treatment can be possibly applied for patients with EGC using these four independent risk factors for lymph node metastasis in EGC. For mucosal cancers, EMR is indicated for EGCs without lymph node involvement based on tumor size and histology. When we found LBVI by pathologic examination after EMR, gastrectomy with D1 lymph node dissection is mandatory. For submucosal cancers, patients with small tumors could be treated with laparoscopic wedge resection without lymph node dissection. However, patients with larger sized tumors or tumors with LBVI should be treated with extended (D2) lymph node dissection.
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