Features of anorectal function after radiation therapy in patients with rectal cancer

Abstract

Purpose of the study. To study the function of the sphincter in patients with rectal cancer after chemoradiotherapy using the method of high-resolution anorectal manometry.Materials and methods. The study included 30 patients with cancer of the middle and lower ampullary rectum, who underwent combined treatment at the National Medical Research Center of Oncology. The patients underwent a course of neoadjuvant gamma radiation therapy using capecitabine. High-resolution anorectal manometry was performed before the start of treatment and 2 months after completion of chemoradiotherapy to study the functional parameters of the sphincter apparatus. The severity of anorectal dysfunction was assessed using the Wexner anal incontinence scale.Results. According to high-resolution anorectal manometry, the average pressure of the anal canal at rest decreased by 1.4 times (p < 0.05), and the average absolute compression pressure with voluntary contraction decreased by 1.2 times (p = 0.0012) after neoadjuvant chemoradiotherapy. A comparative assessment of the maximum absolute compression pressure at this stage of treatment did not allow us to trace a significant difference between its value before the start of radiation therapy and 2 months after its completion (p > 0.05). An increase in threshold sensitivity volumes was noted in 23 patients (p = 0.16). The use of the Wexner scale didn’t show a statistically significant change in the median scores according to the results of patient surveys following the completion of treatment (5.2 vs. 5.5 points, p > 0.05).Conclusions. Radiation therapy has an effect on anorectal function, which may contribute to the occurrence of low anterior resection syndrome after surgical treatment. For this reason, it is now necessary to carefully consider the risks of developing anorectal dysfunction. Equally important is the use of methods for the prevention of low anterior resection syndrome for patients who have received combined treatment for rectal cancer.