The transanal endoscopic microsurgery procedure: standards and extended indications.

Transanal endoscopic microsurgery (TEM) was developed in the early 1980s as a minimally invasive technique allowing the resection of benign rectal adenomas. For this indication, TEM was reported to be safe and effective and even exceeded the results compared to classical local excision. Unsurprisingly, the indication expanded to small rectal cancer. There is still much debate, though, whether it is oncologically safe to perform TEM for rectal cancer. Much has been published about the need for proper patient selection, i.e. patients presenting a low-risk T1 rectal cancer seem to be the most adequate subgroup for this technique. Nevertheless, TEM remains controversial concerning high-risk T1 rectal adenocarcinomas and deeper infiltrating tumors. Several retrospective case series and a small prospective study suggest that radiochemotherapy before local excision reduces recurrence to a level comparable with classic radical surgery (total mesorectal excision). However, these studies are collectively limited, and prospective data from larger multicenter trials are awaited. Reports about functional results after TEM have shown that the procedure has no permanent impact on anorectal function. Even if transient anal resting pressure weakening has been repeatedly described, patients do not suffer from any long-term functional sequelae. Nor do they complain of quality of life impairment.