Abstract： Objective To investigate the application value of transanal endoscopic inter-sphincteric resection(taE-ISR)in sphincter preservation for low rectal cancer.Methods The pro-pensity score matching and retrospective cohort study was conducted.The clinicopathological data of 278 patients with low rectal cancer who were admitted to 5 medical centers,including Ruijin Hospital of Shanghai Jiaotong University School of Medicine etal,from January 2017 to December 2021 were collected.There were 178 males and 100 females,aged 58(range,49-64)years.Of 278 pati-ents,147 cases undergoing taE-ISR were divided into the taE-ISR group,and 131 cases undergoing intersphincteric resection(ISR)were divided into the ISR group.Observation indicators:(1)propen-sity score matching and comparison of general data of patients between the two groups after matching;(2)comparison of intraoperative and postoperative conditions between the two groups;(3)long-term follow-up of the two groups;(4)analysis of risk factors affecting sphincter preservation for low rectal cancer.Propensity score matching was done by the 1:1 nearest neighbor matching method,with a caliper value of 0.05.Propensity score matching analysis was done using the Matching package.Measurement data with normal distribution were represented as Mean±SD,and comparison between groups was conducted using the Student's t test.Measurement data with skewed distribution were represented as M(Q1,Q3),and comparison between groups was conducted using the Wilcoxon rank sum test.Count data were described as absolute numbers or percentages,and comparison between groups was conducted using the Pearson chi-square test or Fisher exact probability.The Kaplan-Meier method was used to calculate survival rate and plot survival curve,and the Log-Rank test was used for survival analysis.Multivariate analysis was conducted using the Logistic regression model with the"glm2"package.The forest plot was used to show the risk factors affecting sphincter preser-vation for low rectal cancer.Results(1)Propensity score matching and comparison of general data of patients between the two groups after matching.Of 278 patients,180 cases were successfully matched,including 90 cases in the taE-ISR group and 90 cases in the ISR group,respectively.After propensity score matching,the elimination of distance between ischial tuberosities and distance from ischial tuberosity to the skin of buttocks confounding bias ensured comparability between the two groups.(2)Comparison of intraoperative and postoperative conditions between the two groups.Cases with positive distal margins,cases with specimen integrity,cases with sphincter preservation were 1,88,88 in the taE-ISR group and 8,78,74 in the ISR group,showing significant differences between the two groups(P＜0.05).(3)Long-term follow-up of the two groups.The median follow-up time was 4.3(range,3.8-5.0)years of the taE-ISR group and 4.1(range,3.4-4.7)years of the ISR group.The overall survival rate,disease-free survival rate and cumulative recurrence rate were 100.0％,95.6％and 2.2％of the taE-ISR group,versus 98.9％,87.8％and 10.0％of the ISR group,showing no significant difference in overall survival rate between the two groups(x2=0.97,P＞0.05)and significant differences in disease-free survival rate and cumulative recurrence rate between the two groups(x2=4.05,5.26,P＜0.05).(4)Analysis of risk factors affecting sphincter preservation for low rectal cancer.Results of multivariate analysis showed that taE-ISR,distance from the tumor to the anus,and adjacent organ damage were independent factors affecting sphincter preservation for low rectal cancer(odds ratio=0.86,0.88,1.35,95％confidence interval as 0.79-0.93,0.83-0.92,1.04-1.74,P＜0.05).In further analysis,there were significant differences in sphincter preservation and defecatory dysfunction between the 21 cases with neoadjuvant therapy in the taE-ISR group and the 19 cases with neoadjuvant therapy in the ISR group(P＜0.05).Conclusions The taE-ISR is safe and feasible for patients with low rectal cancer.Compared with ISR,taE-ISR can significantly improve surgical quality,sphincter preservation rate and patient prognosis.