To investigate the learning curve and short-term outcomes of two minimally invasive procedures for low rectal cancer: transanal total mesorectal excision (TaTME) versus laparoscopic radical resection for middle and low rectal cancer.

A total of 149 patients with low rectal cancer were prospectively enrolled from January 2022 to January 2025. They were randomly divided into the observation group (n=75, treated with TaTME) and the control group (n=74, treated with laparoscopic radical resection for middle and low rectal cancer) using a random number table method. The χ² test or t test was used to compare baseline characteristics and learning curves between the two groups, as well as perioperative indicators, short-term outcomes, and postoperative complication rates at different learning stages.

The inflection point of the learning curve appeared later in the observation group (at the 40th case) and earlier in the control group (at the 20th case). The learning curve of TaTME showed a steeper slope during the learning phase (before the inflection point), with a more excessive increase in operative time. In contrast, the learning curve of laparoscopic radical resection rose more gently. In the observation group, operative time, extubation time, and hospital stay were significantly shorter in the plateau phase than in the ascending phase; intraoperative blood loss and intraoperative drainage volume were also significantly reduced (P<0.05). During the ascending phase, operative time was significantly longer, and intraoperative blood loss and drainage volume were significantly higher in the observation group than in the control group (P<0.05). In the plateau phase, operative time remained significantly longer in the observation group, but intraoperative blood loss and drainage volume were significantly lower than those in the control group (P<0.05).In the observation group, time to first ambulation and time to first flatus were significantly shorter in the plateau phase than in the ascending phase. The complete mesorectal excision rate was significantly higher in the plateau phase, while the positive circumferential resection margin rate and anal function score were significantly lower (P<0.05). The incidence of anastomotic leakage and overall complications in the observation group was significantly higher in the ascending phase than in the plateau phase, and also significantly higher than that in the control group at the same stage (P<0.05).

TaTME has a longer learning curve and greater technical difficulty in the early phase, with longer operative time and significantly higher complication risk during the ascending phase. However, the plateau phase is associated with significantly better intraoperative hemostasis, postoperative recovery, and oncological quality compared with the ascending phase, and is partially superior to the laparoscopic procedure. These findings indicate that TaTME has favorable clinical value and safety after proficient mastery.