A large endoscopic resection by endoscopic submucosal dissection procedure for early gastric cancer.

Gastrectomy with lymph node dissection has provided an excellent therapeutic outcome for patients with early gastric cancer, with a 5-year survival rate of 96%. The prevalence of lymph node metastasis of intramucosal- and submucosal-invading cancer was reported as approximately 3% and 20%, respectively, which means surgery may have been excessive for many patients with these diseases. The endoscopic distinction between mucosal and submucosal invasion is made correctly in only approximately 80% of tumors. However, this means that the pretreatment diagnosis is incorrect for 20% of those tumors otherwise identified as candidates for local treatment. Furthermore, the evaluation of lymphatic-vascular involvement associated with lymph node metastasis is available only through accurate histologic examination. It is essential to evaluate accurately the endoscopically resected specimen and then decide whether or not an additional surgical procedure is warranted. There are several techniques for endoscopic mucosal resection. It is difficult to correctly assess the depth of tumor invasion from resected materials by conventional endoscopic procedures in lesions larger than 15 mm. This is because such lesions often are resected piecemeal because of the size limitation of a resectable specimen. A new endoscopic procedure, endoscopic submucosal dissection, using an insulation-tipped needle knife specifically designed at the National Cancer Center Hospital, Japan, is superior to other endoscopic methods in the treatment of early gastric cancer, and provides an en bloc specimen. En bloc resections allow precise histologic staging and have the potential to prevent recurrent disease.