Although technological advancements have made radiation therapy (RT) treatment more specific to the prostate, surrounding structures such as the bladder and rectum can still be affected.1 Close to 70% of all cancers are treated with radiation; depending on the location of the involved organ, radiation colitis can be a common complication outside of prostate cancer.2 Yet up to 20% of patients with prostate cancer treated with RT (external or internal via brachytherapy) will develop radiation colitis.3

Radiation colitis can present in 2 ways: acute (within 6 weeks of RT) and chronic (within 9 months after RT and for up to 30 years thereafter).1-4 Patients with acute and chronic radiation colitis have similar symptoms, although chronic can cause more gastrointestinal bleeding. A patient’s bowel movements will contain more mucus and will be less formed; they may experience diarrhea as well as urgency. Tenesmus is another common symptom.

Chronic inflammation of the rectum over many years can lead to stricturing of the left side of the colon, which may present with changes in stool caliber or constipation.

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When evaluating patients with prostate cancer for potential radiation colitis, it is important to determine how much radiation they have received, as well as how the RT was delivered. Doses greater than 70 Gy are, for example, associated with higher risk of radiation colitis.4 Brachytherapy utilizes radioactive implants in the prostate to provide radiation, so the effect of the radiation is more likely to be localized and provides less risk of radiation colitis. External radiation poses a greater risk for radiation colitis, however, as the administration field is broader.

Patients with suspected radiation colitis should undergo a full history and physical exam. Outside of radiation colitis, the differential diagnoses for patients with prostate cancer who present with the above symptoms include infection, medications, dietary changes, underlying malignancy, inflammatory bowel disease (IBD), and irritable bowel syndrome. In addition to an in-depth inquiry into prostate cancer history including surgeries, chemotherapies, and radiation therapies, it is important to ask about any other medical conditions such as HIV or IBD that could also predispose these patients to radiation colitis.