Strategy for lymphadenectomy of gastric cancer.

To determine the extent of lymphadenectomy necessary to cure early gastric cancer, the relationship between the frequency of nodal involvements and the extent of the primary invasion was examined in 274 patients with primary cancer of the stomach. We also evaluated the relationship between the number of metastatic lymph nodes, the pattern of metastases to the nodes, and the histologic type of the primary tumor. In early gastric cancer, lymph node metastasis was more frequent in protruded-type cancer with invasion into the submucosa more than 3 cm in diameter and located in the lower third of the stomach, but was limited to the group 1 lymph nodes, which were defined as being anatomically located nearest to the cancer. In cancer invading into the muscularis propria, metastasis to the group 2 or 3 lymph nodes, which were defined as being anatomically located farther from the cancer than group 1, was found. The number of lymph nodes involved and extent of cancer metastasis in these lymph nodes metastasis, differentiated early gastric cancer had more lymph node involvement and wider extent of metastases than undifferentiated cancers. The cancer cells sometimes replaced most of the node and invaded the perinodal fatty tissue, even in early gastric cancer. In addition, it is occasionally difficult to distinguish macroscopically early gastric cancer with submucosal invasion from cancer invaded into the muscle layer. In conclusion, group 1 and 2 lymph nodes, including perinodal fatty tissue, should be removed completely, even in early gastric cancer, except for carcinoma in situ, particularly when the cancer is of the differentiated type.