Laparoscopic intersphincter resection (Ls-ISR) has been used as an extreme anal sparing surgery for low rectal cancer within 5 cm of the anal margin. However, the long-term oncological outcomes and risk factors affecting survival need further clarification.

We retrospectively analyzed patients treated with Ls-ISR between 2012 and 2018. Cox regression analysis of OS and DFS prognostic factors. Kaplan-Meier survival curve was plotted according to prognostic risk factors by Log-rank test.

A total of 177 patients were included in the study, and the median follow-up time was 60 months. Among which, six patients had local recurrence, twenty-five patients had distant metastasis, and 28 patients died. The 1-year, 3-year and 5-year OS rates were 96.0%, 88.7% and 85.2%, respectively. The 1-year, 3-year and 5-year DFS were 94.4%, 85.3 % and 80.0%, respectively, and 5-year cancer-specific survival (CSS) was 88.1%. Univariate analysis showed that age over 60 years, lymph-vascular invasion, nerve invasion, (y)pT3 stage and low differentiation were common risk factors for OS and DFS, and (y)pN+ was a risk factor for DFS. In multivariate analysis, age over 60 years (HR=2.515, 95%CI=1.121~5.642, P=0.025) and (y)pT3 stage (HR=2.591, 95%CI=1.006~6.672, P=0.049) were independent risk factors for OS. Age over 60 years (HR=1.758, 95%CI=1.061~2.912, P=0.028), (y)pT3 stage (HR=2.010, 95%CI=1.090~3.710, P=0.025), (y)pN+ (HR=2.347, 95%CI=1.397~3.945, P=0.001) were independent risk factors for DFS.

Age and stage are important factors affecting the prognosis of low rectal cancer Ls-ISR. Preoperative evaluation of primary tumor stage and lymph node metastasis in order to develop the best surgical treatment strategy.