Predictive factors for lymph node metastasis of differentiated submucosally invasive gastric cancer

For early gastric cancer, submucosal invasion may be unrecognized until histopathologic examination of the specimen obtained by EMR. Gastrectomy with lymphadenectomy is the standard treatment for such submucosal cancers. However, approximately 80% of submucosal cancers do not have lymph node metastasis. Unnecessary surgery could be avoided if a subgroup of patients with submucosal cancer with negligible risk of lymph node metastasis can be defined. This study was conducted to define such a subgroup.

Data from 104 patients surgically treated for differentiated submucosal cancers were retrospectively collected. A multivariate analysis of clinicopathologic factors was performed to identify predictive factors for lymph node metastasis.

Three independent risk factors, namely, female gender (p=0.0174), deep invasion (> or =500 microm) into the submucosal layer (p=0.001), and presence of lymphatic involvement (p < 0.0001) were associated with lymph node metastasis. Lymph node metastasis was not observed in any patient who had limited submucosal invasion and absence of lymphatic involvement. The rate of lymph node metastasis was calculated to be 80% in patients who had both deep submucosal invasion and lymphatic involvement.

If endoscopic resection specimens exhibit no deep penetration (<500 microm) into the submucosal layer and lymphatic involvement is absent, EMR may be sufficient treatment for submucosal well-differentiated early gastric cancers. A long-term follow-up study of patients with such lesions treated by EMR alone is required.