Objective To investigate the clinical efficacy of laparoscopic-assisted inters-phincteric resection (ISR) with different surgical approaches for low rectal cancer.

Methods The retrospective cohort study was conducted. The clinicopathological data of 90 patients with low rectal cancer who were admitted to the Second Affiliated Hospital of Fujian Medical University from January 2016 to December 2020 were collected. There were 58 males and 32 females, aged (60±9)years. Of 90 patients, 60 cases underwent laparoscopic assisted ISR with transpelvic approach, 30 cases underwent laparoscopic assisted ISR with transabdominal and transanal mixed approach. Observation indicators: (1) clinicopathological characteristics of patients with transpelvic approach and mixed approach; (2) intraoperative and postoperative conditions of patients with transpelvic approach and mixed approach; (3) postoperative complications of patients with transpelvic approach and mixed approach; (4) follow-up. Follow-up was conducted by telephone interview and outpatient examination once every 3 months within postoperative 3 years, once every six months in the postoperative 3 to 5 years and once a year after postoperative 5 years to detect tumor recurrence and metastasis, and survival of patients.Follow-up was up to March 2021 or patient death. Measurement data with normal distribution were represented as Mean±SD, and the t test was used for comparison between groups. Measurement data with skewed distribution were expressed as M(range), and comparison between groups was conducted using the non-parametric Mann-Whitney U test. Count data were expressed as absolute numbers or percentages, and comparison between groups was performed using the chi-square test or Fisher exact probability. Comparison of ordinal data was analyzed by the non-parametric rank sum test. Kaplan-Meier method was used to draw survival curves and calculate survival rates, and survival analysis was performed by the Log-Rank test.

Results (1) Clinicopathological characteristics of patients with transpelvic approach and mixed approach. The sex (males, females), distance from the distal margin of tumor to anal margin were 34, 26, (4.5±0.5)cm for patients with transpelvic approach, versus 24, 6, (3.5±0.5)cm for patients with mixed approach, respectively, showing significant differences between them (χ²=4.75, t=8.35, P<0.05). (2) Intraoperative and postoperative conditions of patients with transpelvic approach and mixed approach. The operation time, volume of intraoperative blood loss, distance from the postoperative anastomosis to anal margin were (187±9)minutes, 50(range, 20‒200)mL, (3.4±0.7)cm for patients with transpelvic approach, versus (256±12)minuets, 100(range, 20‒200)mL, (2.6±0.7)cm for patients with mixed approach, showing significant differences between them (t=‒26.99, Z=‒2.48, t=4.67, P<0.05). None of the 90 patients had a positive distal margin. The stoma reversal rates of patients with transpelvic and mixed approach were 93.3%(56/60) and 90.0%(27/30), respectively. Of the 60 patients with transpelvic approach, 3 cases had no stoma reversal due to anastomotic complications, and 1 case was not yet to the reversal time. Of the 30 patients with mixed approach, 2 cases had no stoma reversal due to anastomotic complications, and 1 case was not yet to the reversal time. The 1-, 3-month Wexner scores after stoma reversal were 15(range, 12‒17), 12(range, 10‒14) for patients with transpelvic approach, versus 16(range, 14‒18), 14(range, 12‒16) for patients with mixed approach, showing significant differences between them (Z=‒4.97, ‒5.49, P<0.05). The 6-month Wexner score after stoma reversal was 10(range, 9‒12) for patients with transpelvic approach, versus 11(range, 8‒12) for patients with mixed approach, showing no significant difference between them (Z=‒1.59, P>0.05). (3) Postoperative complications of patients with transpelvic approach and mixed approach. The complications occurred to 16 patients with transpelvic approach and 9 patients with mixed approach, respectively, showing no significant difference between them (χ²=0.11, P>0.05). Cases with postoperative anastomotic fistula, cases with anastomotic bleeding, cases with anastomotic stenosis, cases with intestinal obstruction, cases with incision infection, cases with urinary retention, cases with pelvic infection, cases with pulmonary infection, cases with incisional hernia, cases with chylous fistula, cases with abdominal and pelvic abscess were 5, 2, 1, 7, 0, 1, 5, 3, 1, 1, 1 for patients with transpelvic approach, versus 6, 3, 2, 2, 2, 1, 2, 3, 1, 1, 1 for patients with mixed approach, showing no significant difference between them (P>0.05). The same patient could have multiple postoperative complications. (4) Follow-up. All the 90 patients were followed up for 27(range, 6‒62)months. The follow-up time of 60 patients with transpelvic approach was 27(range, 8‒62)months. The follow-up time of 30 patients with mixed approach was 28(range, 6‒53)months. Of the 60 patients with transpelvic approach, 3 cases had local recurrence, 4 cases had liver metastasis, 3 cases had lung metastasis, and all of them survived with tumor. Of the 30 patients with mixed approach, 1 case had local recurrence, 2 cases had liver metastasis, 1 case had lung metastasis, and all of them survived with tumor. There was no death. The 3-year disease-free survival rates of patients with transpelvic approach and mixed approach were 84.7% and 87.9%, respectively, showing no significant difference between them (χ²=0.39, P>0.05).

Conclusions Lapa-roscopic assisted ISR via transpelvic approach or mixed approach for low rectal cancer are safe and feasible. Compared with transanal mixed approach, the transpelvic approach of laparoscopic-assisted ISR has shorter operation time, less volume of intraoperative blood loss and longer distance from the postoperative anastomosis to anal margin.