Rectal bleeding after radiation therapy for prostate cancer: check for colon cancer, other disease
Endoscopic Evaluation Recommended

by
J. Strax

New York, October 2, 2000 -- Rectal bleeding is a known complication of one common treatment for prostate cancer, external beam radiation. Rectal bleeding can be minimized by use of three-dimensional conformal radiation and by instensity modulated radiation. If it occurs, remedies are applied to treat it. For example, doctors have reported recently that Misoprostol rectal suppositories significantly reduce acute and chronic radiation proctitis (inflammation) in prostate cancer patients.

But what if bleeding caused by some other condition comes along after a man has been radiated for prostate cancer? If a man develops radiation-caused inflammation of the rectum, even toilet paper can cause bleeding. But in older men especially, rectal bleeding may indicate a condition unrelated to radiation therapy. A team at Naval Medical Center San Diego and University of San Diego sought to find out how often rectal bleeding occurs after radiation for prostate cancer, how often some other condition causes it, and how much it affects patients.

Most of us in the activist community want to raise awareness of prostate cancer as a disease that affects many younger men. Yet it is true, as these authors state, that 4 out of 5 men with prostate cancer are older than 65 years. This age group, they point out, "is at increased risk for other disease" including hemorrhoids and anal fissures, diverticular disease, rectal cancer and colon cancer. All of these can show up by way of rectal bleeding, noticed by the patient or found through an occult blood smear test using a mail-in kit or through "heme-positive digital rectal examination (DRE) findings" in the doctor's office.

Men need to make sure that any expectation of rectal bleeding caused by radiation for prostate cancer does not get in the way of finding and treating a separate condition, which may be as life-threatening as the prostate cancer.

The San Diego group looked at 63 patients with prostate cancer who were treated with curative intent or after recurrence. All the men were patients of Peter A. S. Johnstone, MD, between 1993 and 1997. Dr. Johnstone treated them with 60 to 70 Gys of radiation. Using three-dimensional conformal beams and custom blocking significantly lowers the risk of late radiation-induced proctitis after radiotherapy for prostate cancer. From 1996 onward, Dr. Johnstone was in a position to use these 3D techniques. On followup, 30 of his patients had no rectal bleeding. But 33 had at least one episode of bright red blood from the rectum (hematochezia) or showed blood in their stool on the occult blood test he gave after digital rectal exam.

From 5% to 20% of patients who undergo pelvic radiation for prostate cancer may experience proctitis. Proctitis may involve rectal bleeding as well as tenesmus (pain on passing stools), diarrhea and fecal incontinence. What tests should be given to find out if what could be radiation-caused rectal bleeding is just that or comes from another disease, minor or major? And are patients asking for such tests, and doctors offering them?

Some men may be embarrassed to go into detail about rectal symptoms. Or they may be unaware of a need to watch for other, treatable diseases. A man might feel that one blow is enough, lightening does not strike twice in the same spot, and so forth. Meanwhile, busy physicians under the gun from HMO's may go along with reticence. Why bother with more tests requiring complex equipment? As these San Diego physicians say, "In many cases, symptoms are often dismissed as a self-limited annoyance to patients with little endoscopic data to refute other potential causes of hemorrhage."

In this study, if patients complained "of any instance of bright red blood per rectum or had heme-positive stools at DRE," they were referred for scoping of the sigmoid colon (sigmoidoscopy) or colon (colonoscopy). "Referral was made because of the risk of concurrent colorectal disease," the authors state, "and the relative lack of routine endoscopic evaluation in this population."

As mentioned, while 30 out of 63 patients had no bleeding at all, 33 (52%) did have at least one episode or one positive stool test. Of the 33 with bleeding, "five ... were lost to follow-up, one had complaints of rectal bleeding prior to irradiation, and another refused endoscopic evaluation. The remaining 26 patients were referred for various procedures. Of these, 19 (73%) had developed rectal bleeding, and seven (27%) had heme-positive DRE findings."

The hospital's general surgery service examined 19 patients and the gastroenterology service examined seven. Colonoscopy was performed in 17 (65%) of 26 patients, and sigmoidoscopy was performed in nine (35%) of 26 patients. The median time from the end of radiation therapy to endoscopic evaluation was 12 months. Table 2 shows the findings for referred patients.

The San Diego study found that "the likelihood of rectal bleeding symptoms after definitive radiation therapy for prostate cancer approaches 80% at 3 years." Previous reports showed no more than than 60%, but the San Diego study deliberately used a low threshold (one episode of bright red bleeding) so as to track closely what happens to patients.

As to how their findings affect patients, these authors say that while many radiation oncologists try to predict "severity of proctitis relative to the location and total dose of radiation therapy," as far as they know no one does much to rule out other causes of bleeding. Patients generally are not given baseline endoscopy. Some doctors even say that most patients with postradiation therapy bleeding "should be reassured that eventual spontaneous healing is likely to occur and that they should be cautioned against invasive treatment unless absolutely necessary."

But several reasons argue that this is not good enough. The bleeding after radiation therapy for prostate cancer is occurring in "a population of predominantly older men who are subject to various other diseases ... with a pattern similar to that of radiation-induced proctitis." Other men, who have never received radiation for prostate cancer, can expect their internists or family doctors to pay attention to rectal bleeding. "The current consensus regarding the screening and detection of colon and rectal neoplasms clearly indicates that men older than 50 years without prior personal or extensive family history of gastrointestinal malignancy should undergo DRE yearly and DRE with flexible sigmoidoscopy every 5 years (15). Positive DRE findings should be followed by sigmoidoscopy or colonoscopy until the source of bleeding is found."

Men with prostate cancer who are treated with radiation therapy "are no different from the normal, age-matched population in terms of the risk of colorectal abnormalities," these authors say. Patients should get sigmoidoscopy or colonoscopy "if they have rectal bleeding or heme-positive DRE findings at presentation after radiation therapy for prostate cancer to avoid missing such coexistent disease."

Links

Full text article:

Rectal Bleeding after Radiation Therapy for Prostate Cancer: Endoscopic Evaluation Erin M. Moore, MD, Thomas J. Magrino, MD and Peter A. S. Johnstone, MD (Radiology. 2000;217:215-218.)

TABLE 1. Patient and Treatment Characteristics [in new window]

TABLE 2. Endoscopic Findings [in new window]

The Outpatient Evaluation of Hematochezia William N. Segal, M.D. et al, American Journal of Gastroenterology, Feb 1998

Colonoscopy information at National Digestive Disease Clearinghouse

Am J Gastroenterol 2000 Aug;95(8):1961-6 A prospective randomized placebo-controlled double-blinded pilot study of misoprostol rectal suppositories in the prevention of acute and chronic radiation proctitis symptoms in prostate cancer patients. Khan AM, et al, Department of Radiation Oncology, State University of New York Hospital at Stony Brook, 11794-8173, USA.

Lancet 1999 Jan 23;353(9149):267-72 Comparison of radiation side-effects of conformal and conventional radiotherapy in prostate cancer: a randomised trial. Dearnaley DP, et al, Department of Radiotherapy and Oncology, Royal Marsden NHS Trust and the Institute of Cancer Research, Sutton, Surrey, UK.

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