Learning curve of transanal total mesorectal excision for rectal cancer

Abstract

To explore the learning curve of transanal total mesorectal excision (taTME) for rectal cancer. Clinical data of 60 rectal cancer patients undergoing taTME from July 2014 to April 2016 were retrospectively analyzed. According to the sequence of operation date, 60 patients were divided into four groups (A, B, C, D) with 15 cases in each group. General information and perioperative, especially the operative indexes were compared among four groups. There were no significant differences in age, sex, preoperative staging, BMI, tumor size among four groups (all P>0.05). The distance from tumor to anal verge in A group was(6.7±2.5) cm, which was significantly different with B group (4.6±1.2) cm, C group (4.5±1.0) cm and D group (4.0±1.0) cm (P=0.000, P=0.000, P=0.001). Ratio of receiving neoadjuvant therapy was 0, 60.0%(9 cases), 26.7%(4 cases) and 26.7%(4 cases) in A, B, C, D groups respectively with significant difference (P=0.004). Ratio of receiving complete taTME was 73.3%(11/15) in A group, 26.7%(4/15) in B group, 13.3%(2/15) in C group and 26.7%(4/15) in D group, while other patients underwent laparoscopy-assisted procedures. This ratio of A group was significantly higher as compared to B, C, D groups (P=0.003). The operation time was significantly different among four groups [A group (223.0±105.2) minutes, B group (299.0±131.0) minutes, C group(278.0±44.8) minutes, D group (246.0±34.0) min, P=0.035]. Fluctuation of operation time was more common in A and B groups, which became stable in C and D groups. Though intra-operative blood loss was not significantly different among four groups [A group (249.0±559.6) ml, B group (288.0±568.1) ml, C group (87.0±43.3) ml, D group (69.0±64.5) ml, P=0.225], but it presented a decline trend in C and D groups. Number of harvested lymph node from postoperative pathological specimen was 10.9±5.9 in A group, 9.6±2.7 in B group, 15.8±4.8 in C group, and 14.2±5.1 in D group, with significant difference among groups (P=0.008; A group vs. C group, P=0.010; B group vs. C group, P=0.002; B group vs. D group, P=0.021). There were no significant differences in specimen length, postoperative complication rate, distal margin distance and hospital stay. A well-skilled laparoscopic colorectal surgeon, by following the standard surgical procedures, are likely to overcome the learning curve smoothly after performing approximately 30 cases of taTME for rectal cancer.