[Analysis on prognosis and influencing factors of postoperative low anterior resection syndrome for rectal cancer patients undergoing laparoscopic anus-preserving radical resection].

To investigate the prognosis and influencing factors of postoperative low anterior resection syndrome (LARS) for rectal cancer patients undergoing laparoscopic sphincter-preserving radical resection. A retrospective case-control study was used in this study. Clinical data of 268 rectal cancer patients undergoing laparoscopic sphincter-preserving radical resection at Department of Gastrointestinal Surgery of The First Affiliated Hospital of Bengbu Medical College from January 2016 to January 2018 were retrospectively collected. Inclusion criteria: (1) operation procedure was total mesorectal excision (TME) and sphincter-preserving radical resection; (2) rectal cancer was confirmed by postoperative pathology; (3) age of patient was ≥ 18 years old. Exclusion criteria: (1) patient who had history of pelvic surgery and pelvic fractures, which would affect the anorectal function; (2) patient who had history of preoperative chronic constipation and irritable bowel syndrome, which would affect defecation; (3) patient who developed postoperative complications, such as anastomotic leakage, which would affect defecation function; (4) patient who received long-term use of drugs, which would affect the function of gastrointestinal tract or anus; (5) patient suffered from mental illness, who was unable to communicate properly; (6) patient who was lack of clinical data or had incomplete clinical data. Patients were followed up at 3, 6 and 12 months postoperatively, and LARS was diagnosed and graded according to the LARS score scale. The LARS score ranged from 0 to 42 points, and 0 to 20 was difined as no LARS, 21 to 29 was mild LARS, and 30 to 42 was severe LARS. LARS score >20 points at any time point was defined as postoperative LARS. Severe LARS transferring into mild LARS and mild LARS transferring into no LARS was defined as symptom improvement. Incidence and outcomes of LARS were evaluated. The factors associated with LARS outcomes were analyzed using χ(2) test and logistic regression model. A total of 268 patients were enrolled. The incidence of LARS was 42.9% (115/268), 32.5% (87/268) and 20.1% (54/268) at 3, 6, and 12 months postoperatively respectively, and no new case of LARS was found after 3 months postoperatively. The incidence of mild LARS was 25.7% (69/268), 17.2% (46/268) and 8.6% (23/268) at 3, 6, and 12 months postoperatively respectively, and mild LARS incidence at 6 months was significantly lower than that at 3 months (χ(2)=5.857, =0.016), and was significantly higher than that at 12 months (χ(2)=8.799, =0.003). The incidence of severe LARS was 17.2% (46/268), 15.3% (41/268) and 11.6% (31/268) at 3, 6, and 12 months postoperatively respectively, without significant difference among 3 time points (all >0.05). The improvement rate within one year after surgery in patients with mild LARS diagnosed at 3 months was significantly higher than that in patients with severe LARS (88.4% vs. 32.6%, χ(2)=38.340, <0.001). Univariate analysis showed that female, distance from anastomosis to anal verge < 5 cm and tumor diameter ≥ 5 cm were associated with unsatisfied LARS outcomes (all <0.05). Logistic regression analysis showed that distance from anastomosis to anal verge <5 cm was an independent risk factor for LARS outcome (OR=3.589, 95% CI: 1.163 to 2.198, <0.001). The incidence of LARS after laparoscopic sphincter-preserving radical resection decreases with time. The improvement rate within postoperative 1-year of severe LARS is lower than that of mild LARS. Low anastomotic position may lead to impaired improvement of LARS.