Section 6. Digestive organs: Minimally invasive surgery for carcinoid tumors in the rectum

Most carcinoid tumors of the rectum are confined to the submucosa with a size less than 1-2 cm and are usually suitable for local excision, as metastasis to the regional nodes is limited. Endoscopic excision of carcinoid tumors has been performed for this entity as a least invasive method but incomplete resection and/or unclear surgical margin and curability have been reported to occur in 24-42% of cases because of a limited resection up to the submucosal layer and burn effect. Transanal local excision has often been applied for rectal carcinoid tumor as a least invasive method among local excision procedures to accomplish full thickness excision for determining the curability. However, it is often difficult to obtain free access with a sufficient surgical field by the conventional method. Transanal endoscopic microsurgery (TEM) has appeared as a useful option to access a high tumor with fine visibility but special caution has to be taken for tumors sited above the peritoneal reflection. To facilitate full thickness excision even for high tumors, novel local excisional technique called minimally invasive transanal surgery (MITAS) has been developed and used for local removal of carcinoid tumors in the rectum. A specially designed anal retractor connected to the Octopus retractor holder with several novel techniques facilitated excisional procedures around the anus with a sufficient fixed surgical field and an ENDO-stapler allowed the simultaneous excision and anastomosis to be performed. The technique facilitated total excisional biopsy with less operative time and blood loss, and no mobility or mortality in 12 patients with rectal carcinoid tumors.