Transanal endoscopic surgery in rectal cancer

Abstract

Total mesorectal excision (TME) is the standard treatment for rectal cancer, but complications are frequent and rates of morbidity, mortality and genitourinary alterations are high. Transanal endoscopic microsurgery (TEM) allows preservation of the anal sphincters and, via its vision system through a rectoscope, allows access to rectal tumors located as far as 20 cm from the anal verge. The capacity of local surgery to cure rectal cancer depends on the risk of lymph node invasion. This means that correct preoperative staging of the rectal tumor is necessary. Currently, local surgery is indicated for rectal adenomas and adenocarcinomas invading the submucosa, but not beyond (T1). Here we describe the standard technique for TEM, the different types of equipment used, and the technical limitations of this approach. TEM to remove rectal adenoma should be performed in the same way as if the lesion were an adenocarcinoma, due to the high percentage of infiltrating adenocarcinomas in these lesions. In spite of the generally good results with T1, some authors have published surprisingly high recurrence rates; this is due to the existence of two types of lesions, tumors with good and poor prognosis, divided according to histological and surgical factors. The standard treatment for rectal adenocarcinoma T2N0M0 is TME without adjuvant therapy. In this type of adenocarcinoma, local surgery obtains the best results when complete pathological response has been achieved with previous chemoradiotherapy. The results with chemoradiotherapy and TEM are encouraging, but the scientific evidence remains limited at present.

Transanal endoscopic surgery is effective and safe after endoscopic polypectomy of potentially malignant rectal polyps with questionable margins

“…At our unit all candidates for TEM are submitted to the study protocol and are classified into groups according to their preoperative surgical indication (groups I to V) [15]. Patients included in this study underwent a rigid sigmoidoscopy to check the visualization of the scar, its location and its distance from the anal margin.…”

“…All the patients scheduled for TEM undergo the preoperative preparation included in the protocol [15]. The patient's position on the operating room table is determined by the quadrant affected.…”

Low rectal cancer: Sphincter preserving techniques-selection of patients, techniques and outcomes

“…Thus, locally excised pT1sm1 tumors without lymphovascular invasion, up to 3 cm in diameter, have a local recurrence rate of less than 5%, while locally excised pT1sm2-3 tumors have a local recurrence rate of up to 20%, similarly to T2 tumors [72] . Apart from the sm level of invasion, tumor differentiation, vascular or perineural invasion, positive resection margins, lymphocytic infiltration, lymph node spread and tumor budding (presence of neoplastic cells below the invasive front), have been proposed as additional dismal prognostic factors for local recurrence [73] . According to the NCCN guidelines [1] , the standard treatment for T2N0M0 rectal adenocarcinoma is TME without adjuvant therapy per se, since such tumors have a lymph node involvement rate between 12% and 29% [58] .…”

“…With TEM, it is possible to perform local excisions with low risk of perforation at a distance up to 18-20 cm when the tumor is located in the posterior quadrant and up to 15 cm when it is located anteriorly or laterally. The limit for low located lesions is the anal verge itself [73] . The resection bed is usually closed using a running 3-0 polydioxanone (PDS) suture on a small-half needle [64] .…”

“…The pneumorectum is maintained at a constant pressure of 10-12 mmHg which is enough for rectal wall distension and exposure of the tumor. The dissection begins by making a dotted line with the monopolar electric scalpel 10-15 mm from the macroscopic tumor margin [73] . For adenomas located within the intraperitoneal portion of the rectum, a careful mucosectomy, avoiding entry into the peritoneum, is indicated [64] .…”