Radiation Proctitis

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 pelvic radiation treatment for cancers such as cervical cancer, prostate cancer, bladder cancer, and rectal 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.

Signs and symptoms

Acute radiation proctopathy often causes pelvic pain, diarrhea, urgency, and the urge to defecate despite having an empty colon (tenesmus). Hematochezia and fecal incontinence may occur, but are less common. With chronic radiation proctopathy (>3 months), similar symptoms may occur, with rectal bleeding and incontinence occurring more often. In addition, symptoms related to scarring or narrowing of the colon (strictures) or fistulae may occur. Chronic radiation proctopathy presents at a median time of 8-12 months following radiation therapy.

Histopathology

Acute radiation proctopathy occurs due to direct damage of the lining (epithelium) of the colon. Rectal biopsies of acute radiation proctopathy show superficial depletion of epithelial cells and acute inflammatory cells located in the lamina propria. By contrast, rectal biopsies of chronic radiation proctopathy demonstrates ischemic endarteritis of the submucosal arterioles, submucosal fibrosis, and neovascularization.

Diagnosis

Where radiation proctitis is suspected, a thorough evaluation of symptoms is essential. Evaluation should include an assessment of risk factors for alternate causes of proctitis, such as C. difficile colitis, NSAID use, and travel history. Symptoms such as diarrhea and painful defecation need to be systematically investigated and the underlying causes each carefully treated. Testing for parasitic infections (amebiasis, giardiasis) and sexually transmitted infections (Neisseria gonorrhoeae and herpes simplex virus) should be considered. The location of radiation treatment is important, as radiation directed at regions of the body other than the pelvis (eg brain, chest, etc) should not prompt consideration of radiation proctopathy.

Endoscopy is the mainstay of diagnosis for radiation proctopathy, with either colonoscopy or flexible sigmoidoscopy. Proctitis is usually recognized by the macroscopic appearances on endoscopy. Mucosal biopsy may aid in ruling out alternate causes of proctitis, but is not routinely necessary and may increase the risk of fistulae development. Telangiectasia are characteristic and prone to bleeding. Additional endoscopic findings may include pallor (pale appearance), edema, and friability of the mucosa.

Classification

Radiation proctitis can occur a few weeks after treatment, or after several months or years:

• Acute radiation proctitis — symptoms occur in the first 3 months after therapy. These symptoms include diarrhea and the urgent need to defecate.
• 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 characterized 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.

Treatment

Several methods have been studied in attempts to lessen the effects of radiation proctitis. Acute radiation proctitis usually resolves without treatment after several months. When treatment is necessary, symptoms often improve with hydration, anti-diarrheal agents, and discontinuation of radiation. Butyrate enemas may also be effective.

In contrast, chronic radiation proctopathy usually is not self-limited and often requires additional therapies. These include sucralfate, hyperbaric oxygen therapy, corticosteroids, metronidazole, argon plasma coagulation, radiofrequency ablation and formalin irrigation. The average number of treatment sessions with argon plasma coagulation to achieve control of bleeding ranges from 1 to 2.7 sessions.

In rare cases that do not respond to medical therapy and endoscopic treatment, surgery may be required. Overall, less than 10 percent of individuals with radiation proctopathy require surgery. In addition, complications such as obstruction and fistulae may require surgery.

Epidemiology

About 30 percent of individuals who receive pelvic radiation therapy for cancer develop radiation proctopathy.

See also

• Radiation enteropathy