Patients with gastric cancer treated by curative resection had an overall 5-year survival rate of 73.4%. Of these patients, those with early gastric cancer had a 5-year survival rate of 91.6%, while the corresponding value for patients with advanced cancer was 60.1 %. The 5-year survival rate, when analyzed according to the degree of local invasion by gastric cancer, was found to decrease with the increasing depth of invasion. The most striking difference in this regard was observed between cancers which extended as far as, but not beyond, the subserosa and those cancers which had invaded the serosa. The development and availability of adjuvant therapy, effective in the prevention of peritoneal metastasis, is a prerequisite for improvement of the therapeutic outcome of gastric cancer which has invaded the serosa.