Cancer of the rectum is the fifth most common form of cancer in adults worldwide. In 2012, an estimated 40,300 new rectal cancers will be diagnosed in the US with a median age 69 years. Five-year survival rates for rectal cancer are high for early stage disease (90% for Stage I disease) but drop significantly with worsening stage (7% for metastatic Stage IV disease). Recently, advances in neoadjuvant and adjuvant therapy have decreased the rate of local recurrence and improved long-term survival for some patients. Although the treatment for rectal cancer has become increasingly multimodal, surgical excision of the primary tumor remains essential for eradication of disease.

For a long time there has been a debate about the best surgical approach to early stage rectal cancer, whether treatment should involve radical excision (excision of the rectum) or local excision (tumor alone). Proponents of radical surgery argue that excision of the rectum with its surrounding lymphatic drainage offers the best chance for cure. On the other hand, advocates of local excision feel that a less-aggressive approach can avoid the potential ramifications of major pelvic surgery such as sepsis, poor anorectal function, sexual dysfunction, and difficulty with urination and can eliminate the potential need for a permanent stoma. Although the debate has gone back and forth on the adequacy of local excision, there is a growing body of scientific data that suggests that local excision can be sufficient in patients with early rectal cancer of the mid and distal rectum with good histologic features and preoperative imaging (computed tomography, magnetic resonance imaging, and endorectal ultrasound) that shows no evidence of lymph node involvement.

Traditionally, transanal excision has been performed with the conventional technique using traditional equipment. Although this conventional technique can give surgeons operative access to most distal rectal lesions, it can be difficult to conduct on mid-rectal tumors or in large patients with a deep buttock cleft. The technical difficulties experienced under such circumstances can lead to poor visualization, inadequate margins, or specimen fragmentation. In response to the technical limitations of conventional transanal excision, in the 1980s Professor Gehard Buess from Tubingen, Germany, began to develop the technique of transanal endoscopic microsurgery (TEM).

In collaboration with the Richard Wolf Company in Germany, Dr Buess developed the specialized instruments necessary to perform endoscopic surgery transanally. TEM was introduced into clinical practice in 1983, and was gradually implemented in several European countries and eventually introduced in North America and Asia. The last decade has witnessed international growth in the application of TEM yielding a significant amount of scientific data to support its clinical merits and advantages and also shedding some light on its limitations.

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