Radiation-induced proctosigmoiditis occurs most commonly with radiation therapy for cancers of the testes, prostate, urinary bladder, cervix, and uterus ^(23,24).  The incidence of radiation injury is higher in this region of the colon because of the relatively high doses of radiation used for tumors in the pelvic area and the relative immobility of the rectum and sigmoid colon.

The combination of external beam radiotherapy with radiation implants increases damage to the rectosigmoid and is often used for cervical and prostate cancer treatment because of greater efficacy.  Clinically significant radiation proctosigmoiditis requiring therapy occurs in as many as 30% of patients acutely and 15% of patients chronically after pelvic radiation.

In 50% of patients there is acute injury with presenting symptoms of diarrhea and tenesmus without rectal bleeding occurring during radiation treatment or within 6 weeks of treatment completion.

The majority of symptoms resolve within 6 months with conservative therapy only, and flexible sigmoidoscopy usually shows normal findings or minimal nonspecific mucosal changes.  Chronic injury presents with the common symptoms of rectal pain, diarrhea, and rectal bleeding occurring from a latent period of 9 months to 2 years after completion of therapy.

This group may be managed conservatively with steroid enemas, sulfasalazine, and 5-ASA products given either orally or as a rectal enema.  Some benefit has been noted in combining oral sulfasalazine with steroid enemas or in using sucralfate enemas alone.

Patients with significant rectal bleeding requiring blood transfusions have a lower spontaneous remission rate of 0% to 20%, often requiring surgery (~50%) and typically a higher rate of morbidity and mortality.

Figure 5A.  Endoscopic appearance of acute radiation “proctitis.” With the advent of successful endoscopic therapy such as bipolar electrocoagulation or argon plasma coagulation, which are generally safe techniques in the hands of an experienced endoscopist, the frequency of patients requiring surgical therapy has decreased.  Usually patients require multiple sessions of endoscopic therapy before clinical resolution of symptoms is attained (Figures 5A, 5B).  Patients with minimal rectal bleeding requiring no transfusions have a spontaneous remission rate of >70%.

Figure 5B.  Chronic radiation injury to the rectum with telangiectasias.

Deepak V. Gopal, MD, FRCP (C)

Assistant Professor of Medicine
Division of Gastroenterology
Oregon Health & Science University
Portland VA Medical Center
Portland, Oregon

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