Effects of Preoperative Radiotherapy on Long-Term Bowel Function in Patients With Rectal Cancer Treated With Anterior Resection: A Systematic Review and Meta-analysis.

Anterior resection is a common surgical approach used in rectal cancer surgery; however, this procedure is known to cause bowel injury and dysfunction. Neoadjuvant therapy is widely used in patients with locally advanced rectal cancer. In this study, we determined the effect of preoperative radiotherapy on long-term bowel function in patients who underwent anterior resection for treatment of rectal cancer. We performed a comprehensive literature search of the PubMed, Embase, Web of Science, and the Cochrane Library databases. A random-effects model was used in the meta-analysis by the Review Manager software, version 5.3. This systematic review and meta-analysis included 12 studies, which used low anterior resection syndrome score with a total of 2349 patients. Based on them, we concluded that low anterior resection syndrome was significantly more common in the preoperative radiotherapy group (odds ratio 3.59, 95% confidence interval 2.68-4.81,  < .00001) and that major low anterior resection syndrome also occurred significantly more frequently in the preoperative radiotherapy group (odds ratio 3.28, 95% confidence interval 2.05-5.26,  < .00001). Subgroup analyses of long-course radiation, total mesorectal excision, and non-metastatic tumors were performed, and the results met the conclusions of the primary outcomes. Preoperative radiotherapy negatively affects long-term bowel function in patients who undergo anterior resection for rectal cancer.