[From EMR to ESD]

Endoscopic mucosal resection (EMR) has been widely used for endoscopic treatment. Its indication is generally limited to mucosal tumors less than 2 cm in size. Further investigation revealed the criteria for minimal risk of lymph node metastasis even in tumors larger than 2 cm in size. However, using EMR technique, it is difficult to resect such large tumors en bloc, which is required for accurate pathological examination. EMR en bloc was performed to treat such tumors endoscopically, but problems remained because of the reportedly higher recurrence rate after ward. Endoscopists desired to develop a new technique for reliable endoscopic en bloc resection for various lesions, so endoscopic submucosal dissection (ESD) emerged. Several kinds of endoknives for ESD were developed, and submucosal injections of sodium hyarulonate were used to achieve longlasting mucosal elevation, so the ESD procedures capable of resecting larger lesions or lesions with scarring was established. Thus, the indications for endoscopic treatment have expanded. ESD has become widespread in Japan within only a few years, but there are hardly any reports about long-term results. Recently, it was reported that ESD was significantly superior to EMR in terms of the remnant or recurrence rate in the treatment of early gastric cancer. However, further investigation of the long-term results is warranted in early gastric cancers and other gastrointestinal cancers.