Radiation proctitis (and the related radiation colitis) is inflammation and damage to the lower parts of the colon after exposure to x-rays or other ionizing radiation as a part of radiation therapy. Radiation proctitis most commonly occurs after treatment for cancers such as cervical cancer, prostate cancer, and colon cancer. Radiation proctitis involves the lower intestine, primarily the sigmoid colon and the rectum, and is part of the conditions known as pelvic radiation disease and radiation enteropathy.
|Endoscopic image of radiation proctitis before and after therapy with argon plasma coagulation.|
Radiation proctitis can occur a few weeks after treatment, or after several months or years:
- Acute radiation proctitis — symptoms occur in the first few weeks after therapy. These symptoms include diarrhea and the urgent need to defecate, often with pain while doing so (tenesmus). Acute radiation proctitis usually resolves without treatment after several months, but symptoms may improve with butyrate enemas. This acute phase is due to direct damage of the lining (epithelium) of the colon.
- Chronic radiation proctitis — is a widely used term, but is not correct as in long term after radiotherapy, inflammation in the bowel is minimal. The inappropriate name can lead to inappropriate treatment choices. The terms chronic radiation proctopathy—or better, Pelvic Radiation Disease—have been suggested as more accurate alternatives. In the chronic setting the pathological changes are characterised by ischemia and fibrosis. Symptoms may begin as early as several months after therapy but occasionally not until several years later. Symptoms that may manifest include diarrhea, rectal bleeding, painful defecation, incontinence, excess flatulence and intestinal blockage. Intestinal blockage is a result of narrowing of the bowel which blocks the flow of feces. Connections (fistulae) may also develop between the colon and other parts of the body such as the skin or urinary system. Chronic radiation proctopathy occurs in part because of damage to the blood vessels which supply the colon. The colon is therefore deprived of oxygen and necessary nutrients.
Gastrointestinal symptoms occurring in a person who has had exposure to radiation need appropriate investigations to diagnose the nature and the extent of involvement. Symptoms such as diarrhea and painful defecation need to be systematically investigated and the underlying causes each carefully treated. Proctitis is usually recognized by the macroscopic appearances on endoscopy (sigmoidoscopy or colonoscopy) and mucosal biopsy is not needed. Telangiectasia are characteristic and prone to bleeding.
Complications such as obstruction and fistulae may require surgery. Several other methods have been studied in attempts to lessen the effects of radiation proctitis. These include sucralfate, hyperbaric oxygen therapy, corticosteroids, metronidazole, argon plasma coagulation, radiofrequency ablation and formalin irrigation.
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