Anorectal dysfunction in patients with mid-low rectal cancer after surgery: A pilot study with three-dimensional high-resolution manometry

BACKGROUND: The quality of life in patients who develop low anterior resection syndrome (LARS) after surgery for mid-low rectal cancer is seriously impaired. The underlying pathophysiological mechanism of LARS has not been fully investigated. AIM: To assess anorectal function of mid-low rectal cancer patients developing LARS perioperatively. METHODS: Patients diagnosed with mid-low rectal cancer were included. The LARS score was used to evaluate defecation symptoms 3 and 6 mo after anterior resection or a stoma reversal procedure. Anorectal functions were assessed by three-dimensional high resolution anorectal manometry preoperatively and 3-6 mo after surgery. RESULTS: The study population consisted of 24 patients. The total LARS score was decreased at 6 mo compared with 3 mo after surgery (P < 0.05), but 58.3% (14/24) lasted as major LARS at 6 mo after surgery. The length of the high-pressure zone of the anal sphincter was significantly shorter, the mean resting pressure and maximal squeeze pressure of the anus were significantly lower than those before surgery in all patients (P < 0.05), especially in the neoadjuvant therapy group after surgery (n = 18). The focal pressure defects of the anal canal were detected in 70.8% of patients, and those patients had higher LARS scores at 3 mo postoperatively than those without focal pressure defects (P < 0.05). Spastic peristaltic contractions from the new rectum to anus were detected in 45.8% of patients, which were associated with a higher LARS score at 3 mo postoperatively (P < 0.05). CONCLUSION: The LARS score decreases over time after surgery in the majority of patients with mid-low rectal cancer. Anorectal dysfunctions, especially focal pressure defects of the anal canal and spastic peristaltic contractions from the new rectum to anus postoperatively, might be the major pathophysiological mechanisms of LARS.