Ultralow Anterior Resection and Coloanal Anastomosis for Low-Lying Rectal Cancer: An Appraisal Based on Bowel Function

Backgrounds/Aims: On the basis of acceptable oncologic results, ultralow anterior resection (ULAR) and colo-anal anastomosis plus hand-sewn coloanal anastomosis have been performed for treating very low-lying rectal cancer. However, many patients experience bowel dysfunction after ULAR. Studies have provided inadequate data on bowel dysfunctions and only a few functional studies have focused on low rectal cancer. Therefore, we aimed to elucidate the severity of bowel dysfunction after ULAR in a single-surgeon cohort. Methods: In this prospective observational study, we analyzed data of 203 patients who underwent sphincter-preserving surgery for low-lying rectal cancer (tumor located within 5 cm from the anus) between January 2011 and December 2014. During routine follow-up, examinations (3–6 months interval) after ileostomy closure, patients were asked about their bowel functions based on the Wexner incontinence and LAR syndrome (LARS) scores. Patients were divided into 2 groups: LAR group (LAR with double-stapled anastomosis) and ULAR group (ULAR with coloanal anastomosis), and functional scores were compared between 6 and 36 months. Seven risk factors for major LARS were analyzed. Results: At 36 months after surgery, 94.2 and 70.6% of patients in the ULAR group still had moderate to severe incontinence and major LARS respectively. Fecal incontinence improved significantly over time (ULAR group, 14.4 vs. 7.2, p = 0.045; LAR group, 13.9 vs. 5.4, p < 0.05). However, improvement in LARS over time was observed in the LAR group only (26.5 vs. 19.7, p = 0.045). In the ULAR group, the difference did not reach a statistical significance (33.6 vs. 26.0, p = 0.10). Major LARS and moderate incontinence were significantly higher in the ULAR group than in the LAR group (70.6 vs. 47.6%, p = 0.001; 82.4 vs. 32.0%, p = 0.012 respectively). Among the 7 factors evaluated in multivariable analysis, old age (> 70), male sex, ULAR per se, and chemoradiation therapy were found to be meaningful risk factors for major LARS. Conclusion: In patients with low rectal cancers undergoing ULAR plus coloanal anastomosis, bowel dysfunctions were severe. Bowel dysfunctions improved over time, but most patients still experienced major bowel dysfunctions even 36 months after surgery. Risk factors for bowel dysfunctions were old age, male sex, adjuvant chemoradiation therapy, and ULAR. Therefore, ULAR should be performed in carefully selected patients with low-lying rectal cancer.