Radiation proctitis, also referred to as radiation enteropathy, is a rare disorder in which radiation treatment targeting cancers of the rectum, cervix, anus, prostate, or urinary system causes severe mucosal damage to the sigmoid colon, rectum, or lower intestine. Radiation proctitis can be divided into acute and chronic cases.

Onset of acute cases is related to direct mucosal injury and occurs within weeks (<6 weeks) of radiation treatment; it will generally dissipate upon cessation of therapy. Chronic cases may begin several months to years following radiation therapy, with progressive narrowing or obstruction of the rectum, constriction of blood vessels of the colon, and development of fistulas. Rectal pain, diarrhea, tenesmus, and passage of mucus may be symptoms. Rectal bleeding is more often severe in chronic proctitis.

The mainstay of treatment is supportive care for both acute and chronic cases. Colonoscopy with biopsy aids in excluding other causes of mucosal injury.