Background: Endoscopic submucosal dissection (ESD) is widely accepted in Japan for early gastric cancer. Indication for this less invasive treatment is early cancer confined in the mucosa, 20 mm or less in diameter in differentiated carcinoma, and 10 mm or less for undifferentiated carcinoma, because the cancer can usually be completely removed and lymph node metastasis is extremely rare. When the tumor exceeds in size or in depth of invasion beyond the above-mentioned criteria, lymph node metastasis becomes more likely and standard gastrectomy may be indicated. As we previously reported, however, positive rate for lymphnode metastasis is as low as 10 % in this group and parameters to predict lymphnode metastasis include tumor size and cancer invasion to lymphatic vessels. It is thus reasonable to remove the primary lesion by ESD for detailed pathologic examination and, if the risk factor(s) are identified, lymphatic basin potentially positive for metastasis is laparoscopically resected for further treatment. When the lymphnode positive for metastasis is identified, gastrectomy is indicated for potential residual cancer cells. When the negative result is obtained, the patients can be subjected for follow-up without further treatment.
Method: Among the 158 cases with early gastric cancer in which primary lesion(s) were treated by ESD, 17 cases ware diagnosed for potentially positive for lymphnode metastasis. Mean prediction values for metastasis positive rate was 13%. Laparoscopic lymphatic basin dissection was performed in these cases.
Results: Responsible lymphnode basin was identified with ICG endoscopically injected around the ESD scar. Lymphatic vessels and nodes were identified with either laproscopic observation or infra-red laparoscopy. The upper lesser curvature lymphnodes were completely dissected in 13 cases, the upper lesser and greater curvature in 2 cases, and lower lesser and greater curvature in 2 cases, respectively. Mean duration of operation was 258 min, and post-operative course was uneventful except for one case who needed re-operation for ischemic perforation of the lesser curvature. There were two cases in which metastatic positive lymphnodes were identified, and both of them denied further treatment and were subjected to strict follow-up. The mean duration of follow up is 25 mo (2-62mo), and no cancer recurrence is identified. Quality of life is fur much better in this group when compared to any type of series of gastrectomy.
Conclusion: Although indication and steps in this treatment is somewhat complicated, ESD and lymphatic basin dissection serves as ultimate function preserving treatment for early gastric cancer.