Anorectal functional outcomes after transanal total mesorectal excision (TaTME): a Random Forest analysis to predict patients' outcomes

Abstract

Background. Anorectal, sexual and urinary dysfunctions are still common issues after rectal cancer surgery, although seldom explored. Objective. To investigate the entire spectrum of anorectal urinary, and sexual functional outcomes in patients treated with trans-anal total mesorectal excision (TaTME). Design. Patients with a mid-/low-rectal cancer (1-11 cm from the anorectal junction) treated with TaTME between 2015-2020, were interviewed after surgery using validated questionnaires. Statistical analyses were computed to identify variables correlated with worse outcomes and to provide a decision tree algorithm. Setting. University Research Hospital, high volume referral center for rectal cancer surgery. Patients. Patients were included if undergoing TaTME with primary anastomosis with or without diverting ileostomy/colostomy. Only patients with a minimum follow-up of 6 months (from stoma reversal or from the primary procedure) were selected. Interventions. Patients were interviewed using the CCFIS - Wexner Scale, LARS score, ICIQ-MLUTS, ICIQ-FLUTS, IIEF and FSFI questionnaires. Main Outcome Measures. The primary outcome measure was the bowel function. Secondary outcomes were urinary and sexual functional data. Results. Out of 154 patients treated with TaTME, 97 were included (mean age: 66.1 years, M/F 1.7). Sixty-seven percent underwent NAD and 88.7% had a protective stoma. Patients were interviewed in a mean time of 19.0±9.3 months after primary or stoma reversal surgery. Mean Wexner score was 3.8±4.8, whereas mean LARS score was 17.4±13.8. Statistical analyses documented that increased age, operative time and interval to stoma reversal correlated with worse Wexner-LARS categories. The Random Forest analyses documented worse LARS symptoms among patients with an operative time>295 minutes and a stoma reversal performed after more than 5.6 months. Among those who carried a stoma from 3-5.6 months, patients older than 65 years reported anorectal postoperative dysfunction. Limitations. Single center experience with no comparison group. Conclusions. TaTME can provide good long-term results for the anorectal functions. An algorithm with specific risk categories was provided to identify sub-groups at risk to develop major LARS syndrome.