[Discussion on the mechanism of anal sphincter insufficiency caused by radiotherapy in patients with rectal cancer].

At present, radiotherapy as an auxiliary treatment for rectal cancer is widely used in clinic. Although radiotherapy has significant effect on reducing tumor stage, improving anus preservation rate and less tumor recurrence, radiotherapy will damage the anal function and seriously affect the quality of life of patients. Anal sphincter plays an important role in anal function. There are three main damage effects of radiotherapy on anal sphincter: first, the increased deposition of collagen in internal anal sphincter (IAS); second, the destroyed ultrastructure of external anal sphincter (EAS); third, degenerative lesions of the perianal nerve. This article reviews these three points, in order to provide a certain theoretical basis for how to reduce the incidence of anal dysfunction caused by radiotherapy.