Transanal Surgery for benign tumor or early rectal cancer: state of the art and future prospects of the surgeon

The Parks' procedure ( 1973) is the most recognized conventional transanal excision (TAE). A full-thickness en-bloc excision allows an entire resection of the rectal wall with a good pathologic staging. Buess et al. published in 1988 an innovative transanal endoscopic microsurgery (TEM) allowing access to larger and higher tumors. The initial results were very encouraging with a low complication rate of 5%. Compared to TAE, this technique has proven its superiority in terms of negative resection margin, fragmentation of the specimen, postoperative morbidity and local recurrence rate. Indications are now well established. The issue is mainly based on the risk of lymph node involvement that is in particular directly related to the depth of invasion but also to others poor pathologic features. The endoscopic mucosal resection (EMR) seems to be inferior to the TEM due to a piecemeal resection and a partial staging. However the endoscopic submucosal dissection (ESD) competes with surgical techniques, especially for tumors larger than 2 cm. To date there is no recommendation in favor of ESD or TEM for the management of large benign rectal adenomas or early rectal cancer. The concept of organ preservation has emerged due to the high rate of morbi-mortality and to the functional consequences of major rectal surgery. Recent studies are trying to select good responders after neoadjuvant treatment that could benefit from a local excision. The oncologic results of recent trials such as GRECCAR II are promising with no difference in term of oncologic outcomes with the radical surgery group. But the problem remains the specific morbidity of the completion total mesorectal excision in case of poor pathologic features. A rigorous selection of patients and in particular according to the analysis of the tumor response is needed.