Background: Early gastric cancer can be treated by endoscopic excision or simple wedge surgical resection. Standard gastrectomy often is advised if submucosal invasion is found, even though only 15-25% of these patients have lymph node metastases. In this study, the risk of lymph node involvement was examined by multivariate analysis to develop a simple discriminant function for surgical decision making in this setting.
Methods: The authors determined factors significantly correlated with lymph node involvement in a retrospective review of 196 patients with gastric adenocarcinoma invading into, but not beyond, the submucosa. Depth and horizontal spread of cancer in the submucosa were evaluated in addition to ordinary pathologic factors. Discriminant analysis for lymph node involvement was performed using explanatory variables chosen from the results of the univariate analyses.
Results: Lymph node involvement correlated significantly with larger tumor size; greater dimension of submucosal invasion; deeper submucosal invasion; gross appearance of Type I, IIc + III or IIa + IIc; and severity of vessel invasion. Of the variables, the amount of lymphatic invasion, macroscopic appearance, and maximum dimension of submucosal infiltration were selected as effective predictors of lymph node involvement according to discriminant analysis. A correct discrimination of 74.8% was obtained with a linear discriminant function using these variables. Lymph node involvement was observed in 50% of the cases with a discriminant score less than -1 and in 25% of those with a score between -1 and 0, whereas no lymph node involvement was observed in those with a score greater than 2.
Conclusions: Discriminant function as used in this study provided a useful criterion for additional surgery for patients with gastric carcinoma invading the submucosa who were treated initially by localized excision. Prophylactic lymph node dissection may not be necessary for a discriminant score greater than 2, whereas extended lymphadenectomy would be recommended for a score less than -1.