Abstract: Objective To explore the application effect of colonic anal anastomosis and intersphincterectomy in the treatment of low rectal cancer with anal preservation and their impact on postoperative defecation function.Methods A retrospective analysis was conducted on 108 patients who underwent anal sphincter preservation surgery for low rectal cancer in hospitals from February 2019 to January 2024.According to the treatment plan,they were divided into an observation group (n=56) and a control group (n=52).Compare the surgical outcomes,Wexner anal incontinence score,anal pressure,and tumor markers between two groups.Results The observation group [(7.02±2.14) d] had a shorter discharge time than the control group [(10.02±2.06) d] (P<0.05).At 6 and 12 months after surgery,the Wexner Fecal Incontinence Score（Wexner FIS） in the observation group [(3.58±0.92)points and (2.06±0.52) points] was lower than that in the control group [(4.86±0.71) points and (3.31±0.49) points] (P<0.05).After surgery,the resting pressure of the anal canal,maximum systolic pressure of the anal canal,and maximum tolerance of the rectum decreased in both groups (P<0.05),with the observation group [(32.07±6.61) mmHg,(120.81±9.06) mmHg and (120.54±14.38) ml] being higher than the control group [(29.19±5.73) mmHg,(115.73±8.75) mmHg and (112.47±15.96) ml] (P<0.05).After surgery,CEA and CA199 decreased in both groups (P<0.05),with the observation group [(17.53±2.19) ng/ml and (41.06±3.97) U/ml] being lower than the control group [(19.08±3.62) ng/ml and (45.82±4.15) U/ml](P<0.05).Conclusion Both intersphincterectomy and colorectal anastomosis can achieve anal preservation treatment for low rectal cancer,and colorectal anastomosis is more helpful in improving patients' postoperative defecation function.

Key words: colonic anal anastomosis, intersphincterectomy, low rectal cancer, protecting the anus, defecation function