Analysis of Clinical Factors Associated with Anal Function after Intersphincteric Resection for Very Low Rectal Cancer

PURPOSE: The purpose of this study was to identify factors that have a negative impact on anal function after intersphincteric resection. METHODS: We evaluated postoperative anal function in 96 patients with very lower rectal cancer who underwent intersphincteric resection by having patients fill out detailed questionnaires at 3, 6, 12, and 24 months after surgery. Univariate and multivariate analysis based on the Wexner incontinence score were used to identify factors associated with poor anal function after intersphincteric resection. RESULTS: The mean Wexner score at 12 months after stoma closure was 10.0. Patients with frequent major soiling showed a Wexner score of >= 16, and this score was used as a cutoff value of poor anal function. In the univariate analysis, poor anal function was significantly associated with a greater extent of excision of the internal sphincter and with preoperative chemoradiotherapy. In the multivariate analysis, preoperative chemoradiotherapy was the only independent factor associated with poor anal function after intersphincteric resection (odds ratio=10.3; 95 percent confidence interval, 2.3-46.3, P < 0.01). CONCLUSIONS: Preoperative chemoradiotherapy was identified as the risk factor with the greatest negative impact on anal function after intersphincteric resection, regardless of extent of excision of the internal sphincter.