OBJECTIVETo investigate the risk factors of low anterior resection syndrome (LARS) after anal sphincter preserving surgery (SPS) for rectal cancer patients.

METHODSClinicopathological and follow-up data of rectal cancer patients who underwent SPS from January 2010 to June 2014 in Department of Gastroenterological Surgery, Peking University People's Hospital, were retrospectively analyzed. Patients receiving permanent colostomy and local resection were excluded. Meanwhile, during October 2014 and March 2015, the enrolled patients were asked to fill out a specially designed questionnaire for LARS through face-to-face interview or telephone inquiry, according to the chronological order of operation. Based on the score of questionnaire, patients were divided into three groups: 0-20 points: non LARS; 21-29: minor LARS; 30-42: major LARS. The demographic and clinicopathologic features were compared among groups and the risk factors of major LARS were tested by logistic regression analysis.

RESULTSA total of 100 patients (61 males, 39 females) completed the bowel function survey, with an average age of 66.2(41-86) years, 33 patients <60 years versus 67 patients ≥60 years. No significant difference was observed in age distribution (P=0.204). Interval from operation to first follow-up was more than 1 year in 70 patients, and the median follow-up was 23 months. Thirty-seven patients were non LARS, 18 were minor LARS and 45 were major LARS. No significant differences in clinicopathological data (all P>0.05) were observed among three groups except radiotherapy history (P=0.025), tumor location(P=0.000) and distance from anastomotic site to anal verge(P=0.008). After comparison of non LARS group combined with minor LARS group versus major LARS, re-analysis of risk factors showed that radiotherapy history (RR=5.608, 95%CI:1.457 to 21.584, P=0.006), distance from tumor lower margin to anal verge (RR=0.125, 95%CI:0.042 to 0.372, P=0.000), distance from anastomotic site to anal verge (RR=0.255, 95%CI:0.098 to 0.665, P=0.004) and preventive ileostomy history(RR=3.643, 95%CI:1.058 to 12.548, P=0.032) were associated with major LARS. One potential risk factor detected in combined analysis was female (RR=2.138, 95%CI: 0.944 to 4.844, P=0.078). Multivariate analysis revealed that female (RR=2.654, 95%CI: 1.005 to 7.014, P=0.049), radiotherapy history (RR=10.422, 95%CI:2.394 to 45.368, P=0.002) and distance from tumor lower margin to anal verge ≤7 cm (RR=8.935, 95%CI:2.827 to 28.243, P=0.000) were independent risk factors of major LARS.

CONCLUSIONSLARS is a significant problem in most rectal cancer patients after SPS. The risk of major LARS increases on condition of radiotherapy, low tumor position and female. When dealing with these patients, preventive measures should be taken into consideration during SPS.