To compare the short-term and long-term efficacy of transanal minimally invasive surgery (TAMIS) and transanal endoscopic microsurgery (TEM) in local resection of rectal tumors.

The retrospective cohort study was conducted. The clinical data of 52 patients with rectal tumors who were admitted to Daping Hospital of Army Military Medical University from April 2012 to June 2021 were collected. Twenty-six patients undergoing TEM surgery were allocated to the TEM group, and 26 patients undergoing TAMIS were allocated to the TAMIS group. General data, perioperative indicators, complications and disease-free survival were compared between the two groups.

There were no significant differences in gender, age, American society of anesthesiologists classification, tumor distance from anal margin, tumor diameter and pathological type between the two groups (P＞0.05). All patients successfully completed the operation without intraoperative complications. The operative time and blood loss in TEM group were (80.9±39.0) min and (22.0±23.7) mL, respectively. The operation time and blood loss in TAMIS group were (90.0±27.0) min and (24.8±20.7) mL, respectively. There was no significant difference in the above indexes between the two groups (t=-0.960, -0.449; P＞0.05). No postoperative complications occurred in the TEM group. In the TAMIS group, one patient developed pelvic infection after operation, and was discharged successfully after anti-infection treatment. There were no significant differences in the time to first flatus, time of first clear-fluid diet and the length of postoperative hospital stay between the two groups (t=0.610,-1.091,-1.675;P＞0.05). Pathological examination confirmed that the surgical margin and basal margin of all patients were negative. In the TEM group, one patient with rectal adenoma had local recurrence 1 year after surgery. In the TAMIS group, one patient with early rectal cancer developed liver and lung metastasis 8 months after surgery. The 3-year disease-free survival rates of the TEM group and the TAMIS group were 95.5% and 93.8%, respectively, and there was no significant difference between the two groups (χ²=0.108, P=0.742).

TAMIS is safe and feasible for local resection of rectal tumor, and has similar short-term and long-term oncological outcome as TEM.