A multicentre prospective study of anal function after laparoscopic ultra-low rectal cancer surgery using a mixed-effects model.

Abstract

Abdominoperineal resection with permanent colostomy has historically been performed for very low rectal cancer located near the anal canal. Anus-preserving surgeries, such as intersphincteric resection (ISR) and low anterior resection (LAR), have recently become more common. However, postoperative anal function is a concern in these surgeries when the anastomosis is very low. The aim of this study was to examine changes in anal function and factors that worsen anal function after surgery for rectal cancer. A multicentre (47 facilities), non-randomized, single-arm phase II trial was conducted prospectively using the Wexner score questionnaire between 2014 and 2017. A total of 278 patients who underwent laparoscopic surgery for clinical Stage I very low rectal cancer were analysed using a mixed-effects model. Anal function temporarily worsened 3 months after surgery, but gradually recovered and spontaneously returned to an acceptable level in 3 years. In a comparison of surgical procedures, anal function was significantly better after LAR than after any type of ISR. There was little difference in anal function after total ISR, subtotal ISR and partial ISR. In the mixed-effects model analysis, ISR and older age (≥75 years) were identified as independent factors that worsened postoperative anal function. The results showed early deterioration of anal function followed by gradual improvement to an acceptable level after surgery. There is a higher risk of poor postoperative anal function after ISR and in older patients, and these risk factors should be communicated to patients when obtaining consent for the surgery.