The results and limitations of endoscopic submucosal dissection for colorectal tumors.

In the colorectal tumor, the lesions suitable for the endoscopic treatment are those with no lymph node metastasis such as adenomas, intramucosal cancers, and minimally invasive submucosal cancer (invasion depth 1000 m, well and moderately differentiated type, no lymphovascular invasion). The new endOscopic technique, endoscopic submucosal dissection (ESD) enables en-bloc resection of the lesions regardless of their size and location. In order to perform ESD more easily, safely, and efficiently, we invented water jet short needle knives (Flush knife). Emitting a jet of water from the tip of a sheath enables submucosal local injection with a knife itself without replacement of operative instruments, which leads to efficient treatment. Especially, Flush knife is very effective for the lesions located at lower rectum and anal canal where there are many vessels. We treated a total of 361 colorectal lesions by ESD between June 2002 and July 2007, and en-block complete resection rate was 98.3 %. In 12 cases, "muscle retracting sign" was recognized. This sign is an index of the discontinuation of ESD, but it is impossible to diagnose preoperatively. The postoperative bleeding occurred in 0.8 % (3 cases: no blood transfusion is needed). The intraoperative perforation occurred in 1.9 % (6 cases: 5 cases were treated conservatively, 1 case was treated surgically) and the postoperative perforation occurred in 1 case (0.3%) treated surgically. ESD is the extremely effective treatment for the colorectal tumors and also is possible to be performed safely with the appropriate choice of the devices and strategy for dissection.