What Are the Main Features of a TEM?

Abstract

Transanal endoscopic microsurgery (TEM) was introduced in Germany in the mid-1980s as a new type of transanal local excision technique with the aim of overcoming the difficulties of endoscopic approaches and conventional transanal excision (TAE) in the treatment of large adenomas, specifically those located in the mid- and upper rectum. The main advantages of TEM are the safety of the technique in terms of postoperative morbidity and long-term functional outcomes, especially compared with major abdominal surgery such as anterior resection. Compared with other local approaches (endoscopic and TAE), TEM allows a higher rate of en bloc removal and a tumor-free resection margin, thereby reducing the risk of neoplasm recurrence. However, TEM is not a simple technique to acquire and requires a long learning curve. TEM represents the gold standard for large rectal adenomas, but its role in the management of rectal cancer remains a matter of debate. In this context, TEM is considered oncologically safe, as a primary treatment with a curative intent, only in highly select types of early rectal cancer. Another accepted TEM indication is for more advanced lesions in unfit patients with a palliative intent. Over the last several decades, due to the increasing rate of complete pathological responses to neoadjuvant treatment for rectal cancer, a novel indication is under investigation. TEM has been proposed for patients with a major or complete clinical response to confirm their pathological status while avoiding a total mesorectal excision (TME) and sparing the rectum. The aim of this chapter is to analyze the main technical and oncological features of the TEM technique.