This section describes efficacy outcomes from the published literature that the Committee considered as part of the evidence about this procedure. For more detailed information on the evidence, see the interventional procedure overview.
4.1 A case series of 56 patients with low rectal cancer treated by transanal total mesorectal excision (TaTME) reported an overall survival rate of 96% (54/56) of patients at 5‑year follow‑up (calculated using the Kaplan–Meier estimator); 2 patients with synchronous liver metastases died of metastatic evolution, 1 at 24 months and the other at 37 months after the procedure. The study reported a disease‑free survival rate of 94% (53/56) at 5‑year follow‑up (Kaplan–Meier estimate); 2 patients developed metastases and 1 developed local recurrence.
4.2 The case series of 56 patients reported local recurrence in 1 patient at 24 months; the patient had a median circumferential resection margin of less than 1 mm. A case series of 30 patients reported locoregional or distant recurrence in 40% (12/30) of patients at 21‑month follow‑up.
4.3 A non‑randomised comparative study of 74 patients treated by TaTME or laparoscopic total mesorectal excision (TME) reported that the quality of the mesorectal resection was not significantly different between the groups (p=0.60). In the TaTME group, resection was complete in 92% (34/37) of patients, almost complete in 5% (2/37) of patients and incomplete in 3% (1/37) of patients. In the laparoscopic TME group, resection was complete in 95% (35/37) of patients and almost complete in 5% (2/37) of patients. The patient from the TaTME group who had an incomplete resection had a total colectomy previously. A non‑randomised comparative study of 50 patients treated by TaTME or laparoscopic TME reported that macroscopic evaluation of the completeness of mesorectal excision was significantly better for the TaTME group; 96% (24/25) of the specimens had a complete mesorectum compared against 72% (18/25) of the specimens in the laparoscopic TME group (p<0.05). The case series of 30 patients and 1 case series of 5 patients with rectal cancer treated by TaTME reported that the mesorectum had been completely excised in 100% of specimens.
4.4 The non‑randomised comparative study of 74 patients treated by TaTME or laparoscopic TME reported no circumferential margin involvement in either group. The non‑randomised comparative study of 50 patients reported circumferential resection margins of less than 2 mm in 1 patient of the TaTME group and in 8% (2/25) of patients in the laparoscopic TME group.
4.5 The case series of 56 patients reported conversion to laparotomy (in the group for whom the operation used laparoscopic assistance) in 7% (3/41) of patients; 1 because of adhesions from a previous operation, and 2 because of technical difficulties in obese patients. The case series of 30 patients reported a conversion to open surgery in 7% (2/30) of patients because of the posterior fixation of the tumour.
4.6 The specialist advisers listed key efficacy outcomes as: technical ease of dissecting the rectum low down in a narrow pelvis, quality of low rectal sealing and anastomotic healing, rate of conversion to open surgery, operative time, pain after surgery, quality of the TME specimen, length of stay in hospital, cosmetic outcome, patient‑reported outcome measures, and urinary and sexual function after surgery.