difficulties to recruit all the patients

Local excision for early rectal cancer has proven its feasibility and oncological safety. Indeed, lymph node invasion does not exceed 1% and 10% in pT1sm1 and pT1sm2 rectal carcinomas respectively. Two procedures are currently performed in these early cancers as well as in preneoplastic lesions. Transanal endoscopic microsurgery (TEM), which has proven its superiority over traditional transanal excision, is a surgical approach associated with a 92% R0 excision rate, a survival comparable to radical anterior resection and a low morbidity. It consists of a full-thickness excision. The second procedure is a recently introduced technique: the endoscopic submucosal dissection (ESD), which encompasses only the mucosa and submucosa. ESD enables endoscopists to achieve higher en bloc resection rates than standard mucosectomy and is associated with a 88% R0 resection rate, which decreases to 65% in the subgroup of European series. Though very promising, the role of ESD remains controversial in malignant lesions with few published reports. There are therefore 2 different techniques with 2 different dissections (full-thickness vs. submucosal) to achieve the same oncological treatment. So far, only one retrospective single-center study including 63 patients has compared TEM and ESD in early rectal cancer without finding any difference between the 2 procedures, and there are no other available studies comparing TEM and ESD for any type of colorectal tumor. The aim of the present research is to compare ESD with TEM for early rectal cancer and rectal adenomas for short- and long-term outcomes.

Inclusion Criteria:

• Presenting with an ERT (i.e. rectal adenoma or rectal carcinoma Tis or staged usT1N0 on endorectal ultrasound) that can be alternately resectable by TEM or ESD
• Histology proved by a preoperative biopsy

Exclusion Criteria:

• " Palliative " excision T2/3/4 or N+
• Preoperative radiochemotherapy (down-staging)
• Metastatic cancer
• Pregnant or breast-feeding women