Local excision of T1 rectal cancer: where are we now?

When is local excision appropriate for "early" rectal cancer?

Local excision is increasingly performed for “early stage” rectal cancer in the US; however, local recurrence after local excision has become a controversial issue in Western countries. Local recurrence is considered to originate based on the type of tumor and procedure performed, and in surgical margin-positive cases. This review focuses on the inclusion criteria of “early” rectal cancers for local excision from the Western and Japanese points of view. “Early” rectal cancer is defined as T1 cancer in the rectum. Only the tumor grade and depth of invasion are the “high risk” factors which can be evaluated before treatment. T1 cancers with sm1 or submucosal invasion <1,000 μm are considered to be “low risk” tumors with less than 3.2 % nodal involvement, and are considered to be candidates for local excision as the sole curative surgery. Tumors with a poor tumor grade should be excluded from local excision. Digital examination, endoscopy or proctoscopy with biopsy, a barium enema study and endorectal ultrasonography are useful for identifying “low risk” or excluding “high risk” factors preoperatively for a comprehensive diagnosis. The selection of an initial local treatment modality is also considered to be important according to the analysis of the nodal involvement rate after initial local treatment and after radical surgery.

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.