Occult lymph node metastasis in gastric cancer with submucosal invasion

To evaluate more precisely the incidence of lymph node metastasis in patients with submucosally invaded (sm) gastric cancer, three additional sections were made from the remaining half of 1,794 lymph nodes taken from 57 patients, for a detailed reexamination. Lymph node metastasis was demonstrated in 19 nodes from 11 patients by the initial routine examination; however, the detailed reexamination showed cancer involvement in a further nine lymph nodes from eight patients. Of these eight patients, metastasis had not been detected in any lymph nodes by routine examination in six. Macroscopically, the lesion was of the depressed or mixed type in six of the eight patients. From the intranodal location and growth pattern of the cancer foci, lymph nodes with occult metastasis were divided into the marginal sinus type, the medullary sinus type, and the mixed type, with the marginal type being found most frequently. The overall incidence of lymph node metastasis in patients with sm gastric cancer was as high as 29.8% (17/57) in this series. Moreover, a follow-up study revealed that two patients with occult metastasis died of cancer recurrence postoperatively. Accordingly, systematic regional lymph node dissection should be carried out at the time of surgery for sm gastric cancer.