[Risk factors of coloanal anastomotic stricture after laparoscopic intersphincteric resection for low rectal cancer]

Objective: To evaluate the risk factors of coloanal anastomotic stricture after laparoscopic intersphincteric resection (Lap-ISR) for patients with low rectal cancer. Methods: A retrospective case-control study was performed to collect clinicopathological data from a prospective database (registration number: ChiCTR-ONC-15007506) at the Department of Colorectal Surgery, the Characteristic Medical center of PLA Rocket Force. From June 2011 to August 2018, a total of 144 consecutive patients with low rectal cancer who underwent Lap-ISR were enrolled in the study. Inclusion criteria: (1) reconstruction of digestive tract by end-to-end hand-made coloanal anastomosis (HCAA); (2) distance from lower tumor margin to anorected sphincter ring < 1 cm and distance from lower tumor margin to intersphincteric groove ≥ 1 cm; (3) T1-3 stage tumor with expected negative circumferential resection margin evaluated by preoperative MRI or 3D endoanal ultrasound; (4) rectal cancer confirmed as well- or moderately-differentiated adenocarcinoma; (5) preoperative Wexner incontinence score >10 points. Exclusion criteria: (1) follow-up period less than 3 months; (2) multiple primary cancers; (3) undergoing colonic J-pouch, coloplasty or reconstruction of end-to-side coloanal anastomosis; (4) death within perioperative period (within 3 months after surgery). Coloanal anastomotic stricture was diagnosed if the index finger or 12 mm electronic colonoscope had obvious resistance through the anastomosis or new rectum, or could not pass, accompanied by clinical symptoms such as difficult defecation and anal incontinence. Degree of anastomotic stricture was divided into 3 grades: grade A required anal enlargement, laxative or enema to assist defecation without active surgical treatment; grade B required surgery or endoscopic intervention; grade C required definitive ostomy, including unreducible preventive ileostomy or permanent colostomy. Univariate and multivariate analysis were used to evaluate the effects of 28 variables, including baseline data (age, gender, body mass index, neoadjuvant therapy, etc.), tumor-related factors (distance between tumor low margin and anal edge, maximum diameter of tumor, TNM staging, etc.), surgery-related factors (operation time, intraoperative blood loss, ISR procedure, anastomotic height, etc.) and anastomotic leakage, on the postoperative coloanal anastomotic stricture. Univariate analysis used χ(2) test or Fisher's exact test, then factors with P<0.05 were further included in multivariate analysis using logistic regression. Results: A total of 144 patients were enrolled in the study, including 90 males and 54 females with a median age of 59 years and median BMI of 24.88 kg/m(2). R0 resection rate was 96.5% (139/144). Median tumor distal resection margin was 1.5 (0.5 to 3.0) cm. Median follow-up was 31.5 (4 to 86) months. Coloanal anastomotic stricture was observed in 19 patients (13.2%), including 3 cases (2.1%) of grade A, 9 cases (6.2%) of grade B, and 7 cases (4.9%) of grade C. The median interval from the initial surgery to diagnosis of anastomotic stricture was 7 (1 to 31) months. Univariate analysis showed that male (χ(2)=6.795, P=0.009), radiotherapy (χ(2)=13.330, P=0.001), operation type of ISR (χ(2)=7.996, P=0.013), and anastomotic leakage (χ(2)=10.198, P=0.004) were associated with the postoperative coloanal anastomotic stricture. Multivariate analysis further indicated that male (OR=5.975, 95% CI: 1.209-29.534, P=0.028), postoperative radiotherapy (OR=8.748, 95% CI: 2.397-31.929, P=0.001), and anastomotic leakage (OR=6.313, 95% CI: 1.834-21.734, P=0.003) were independent risk factor of postoperative coloanal anastomotic stricture. Conclusion: For male patients, or patients with postoperative radiotherapy or anastomotic leakage, close follow-up should be carried out to prevent postoperative coloanal anastomotic stricture following Lap-ISR.