Transanal endoscopic microsurgery (TEM): a new technique and development during a time period of 20 years.

The technique of transanal endoscopic microsurgery (TEM) was made available for clinical use in 1983. To our knowledge, this technique is currently the only one-port system in endoscopic surgery by which a direct endoluminal approach to the target organ by using a natural opening of the body. Use of the stereoscopic view also is unique in procedures performed routinely. The first indication for use of this new technique was excision of rectal adenomas. It provided the potential of low complications and low recurrence rates compared with the conventional surgical procedures. With the development of endorectal ultrasound for staging, and because many adenomatous polyps contained early rectal cancer, the question arose as to how to deal with these patients after successful local excision. Studies showed that the indication for use of the TEM-technique was extended to early, good differentiated rectal cancer-so-called, low-risk rectal cancer. Many studies showed that the TEM-technique is the optimal operation to avoid complications for patients with rectal polyps and low-risk pT1 tumours of the rectum. The main problem remains regarding how to identify these patients preoperatively and separate them from those who already have a high risk of local recurrence and lymph node metastasis at the time of operation. The effectiveness of any preoperative or postoperative combined treatment to reduce the risk of local recurrence and lymph node metastasis remains unclear. Combined treatment could be a future option to also cure more advanced cancer. Currently, the TEM-technique is the only endoscopic technique that uses a natural opening to reach the target organ, and is a valuable surgical technique with a low complication rate for patients with adenomatous rectal tumours and early rectal cancer.