[Mechanism by which peritoneal disseminated metastasis develops in gastric cancer]

To clarify the peritoneal dissemination of gastric cancer 270 resected specimens were analyzed by methylene blue formalin fixation staining method. As a result, not only metastasis to lymph nodes but also very small disseminated metastatic lesions which had been overlooked before were observed in the greater omentum and lesser omentum. The relationship among this disseminated lesion, macroscopic peritoneal disseminated metastatic lesion, degree of serosal infiltration, area of infiltration and tissue type of the tumor was studied. The very small disseminated metastatic lesion was judged to be Po, accounting for 15.3 percent and 28.1 percent of 270 resected cases were positive for disseminated metastasis. Disseminated metastasis developed relatively early. The incidence of disseminated metastasis was higher in the poorly differentiated type than in the well-differentiated one. The case which showed break of the capsule of lymph node and infiltration into the area around lymph node accounted for 45.0 percent of the positive cases of lymphatic metastasis. Since very small disseminated lesions are present in the greater omentum, lesser omentum and the area around lymph node as described above, radical operation should been bloc resection of these lesions in gastric cancer.