Endoscopic, transanal, laparoscopic, and transabdominal management of rectal neuroendocrine tumors

Rectal neuroendocrine tumors (RNET) are rare tumors but their prevalence is constantly increasing due to a prolonged survival and rising incidence related to a growing number of colonoscopies and improved knowledge. Their main prognostic determinant is tumor stage. While most RNET are localized, their management should be tailored depending on the presence or absence of the factors predictive of lymph-node metastases including tumor size, endoscopic aspect, T stage, grade and lymphovascular invasion. Endoscopic ultrasonography is the most relevant technique for locoregional assessment. Low-risk RNET can be treated using advanced endoscopic resection techniques or transanal endoscopic microsurgery, in expert centers because they require technicity and experience. Conversely, radical surgery with lymphadenectomy should be proposed in the presence of any pejorative factor. The long-term evolution of RNET remains to be specified, and prospective studies should be conducted in order to determine the relevance of the current management strategies.

[How to standardize transanal total mesorectum excision]

Transanal total mesorectum excision (taTME) is a novel approach to treat rectal cancer by colorectal surgeons. How to standardize taTME is important for colorectal surgeons, especially at their initial attempt. They can start this approach cautiously only after they master skilled laparoscopic technique and pelvic anatomy, get the knowledge of taTME clearly, and are approved by healthcare department. The female patients with age <70 years old, distance of 5 to 7 cm from tumor inferior margin to anal verge, tumor size <3 cm, cTNM stage <T3aN0 are suitable for taTME. The instruments include laparoscopic equipment, anal retractor, anal pathway insufflator with constant pressure. There are three operative approaches, such as pure, combined laparoscopic hybrid and sequential hybrid taTME. The combined approach is easier to perform because it has advantages both of laparoscopic and transanal pathway. TaTME has the advanctages of less invasiveness and fast postoperative recovery, which is in accordance with the concept of enhanced recovery after surgery. This paper discusses the taTME from the following aspects: preoperative preparation, case selection, surgical instruments, surgical skills and perioperative management. We aim to help the colorectal surgeons to initiate taTME earlier, shorten the learning curve, and decrease the complications, resulting in benefits to patients.