Transanal endoscopic microsurgery.

There is increasing interest in organ-preserving options in the management of rectal cancer. Excision of small, early stage cancers by transanal endoscopic microsurgery (TEM) is an important part of this approach. Carefully selected cancers can be treated successfully by TEM with acceptably low risk of recurrent disease and overall cancer outcomes similar to radical surgery. The impact of recurrence can be mitigated by early detection of luminal or nodal disease for which a robust surveillance programme is essential. However, patients with high risk features on post-TEM pathology should be offered completion radical surgery which is associated with good oncological results. There may be an opportunity to expand the population of patients who can be offered rectal preservation with the use of radiotherapy in either adjuvant or neo-adjuvant context. Full thickness excision by TEM may be particularly valuable in those demonstrating a clinical complete response to radiotherapy, where diagnosis of complete pathological response can be confirmed. The use of TEM in managing more advanced rectal cancers is exciting, but must be tested within formal clinical trials before being adopted as routine practice.