Radiation therapy for prostate cancer nearly doubles the risk of rectal cancer

(I-Newswire) April 2, 2005 - "Men who have had prostate radiation should be aggressively monitored for rectal cancer starting five years after treatment," said Nancy Baxter, MD, PhD, lead study author with the University of Minnesota Cancer Center. "This is the first time rectal cancer risk associated with prostate radiation has been quantified, and these findings may also have implications for patients treated with radiation for other pelvic cancers."

Prostate cancer is the most commonly diagnosed malignancy in the United States. Although there is a high rate of survival associated with prostate cancer, a large number of men are left at risk for long-term consequences of their cancer treatment, including the development of other cancers.

Researchers at the University of Minnesota Cancer Center used data from the Surveillance, Epidemiology and End Results (SEER) Registry to evaluate the effect of radiation on development of cancer in the rectum. More than 85,000 men, age 18 to 80, were included in this retrospective, population-based study. Radiation therapy for prostate cancer has been associated with an increased rate of pelvic malignancies, particularly bladder cancer. Findings of this study suggest that direct radiation to the rectum increases the risk of developing rectal cancer, but does not affect the risk of cancer in other parts of the colon.

"While the findings of our study do not suggest that prostate cancer treatment should change, we recommend that the potential for developing rectal cancer be included in conversations between doctors and patients when considering the individualized course of treatment and surveillance for patients with prostate cancer," said Baxter.

Since the study results are based on men who were treated for prostate cancer prior to 1995, the risk of developing cancer may be reduced by the evolution of radiation delivery techniques. However, researchers say that even with today's technology, some portions of the rectum might still receive a high dose of radiation. Therefore, the risk of rectal cancer may still be substantial and thus, until proven otherwise, men treated with radiation for prostate cancer need monitoring for rectal cancer beginning five years after treatment.

Guidelines of multiple agencies and professional societies underscore the importance of colorectal cancer screening for all individuals 50 years of age and older. Approved tests include barium enema, FOBT, flexible sigmoidoscopy and colonoscopy. However, flexible sigmoidoscopy and colonoscopy are the best methods for accurately detecting rectal cancer. Each screening option has advantages and disadvantages. Patients undergoing radiation therapy for prostate cancer are advised to ask their doctor about one of the approved screening methods, regardless of their age.

More information about colorectal cancer screening is available at http://www.gastro.org.

About the Study

Researchers at the University of Minnesota Cancer Center conducted a population-based study using the Surveillance, Epidemiology and End Results (SEER) registry data from 1973 through 1994 to evaluate the effect of radiation on development of cancer in the rectum and the rest of the colon. The study population included men from 18 to 80 years of age who were diagnosed with prostate from January 1, 1973 to December 31, 1994. A total of 30,552 men received radiation, of which 1,437 developed colorectal cancers.

About the AGA

The American Gastroenterological Association (AGA) is dedicated to the mission of advancing the science and practice of gastroenterology. Founded in 1897, the AGA is the oldest medical-specialty society in the United States. The AGA's 14,000 members include physicians and scientists who research, diagnose and treat disorders of the gastrointestinal tract and liver. On a monthly basis, the AGA publishes two highly respected journals, Gastroenterology and Clinical Gastroenterology and Hepatology. The AGA's annual meeting is Digestive Disease Week, which is held each May and is the largest international gathering of physicians, researchers and academics in the fields of gastroenterology, hepatology, endoscopy and gastrointestinal surgery.

About Gastroenterology

Gastroenterology, the official journal of the AGA, is the most prominent journal in the subspecialty and is in the top one percent of indexed medical journals internationally. The journal publishes clinical and basic studies of all aspects of the digestive system, including the liver and pancreas, as well as nutrition. The journal is abstracted and indexed in Biological Abstracts, CABS, Chemical Abstracts, Current Contents, Excerpta Medica, Index Medicus, Nutrition Abstracts and Science Citation Index. For more information, visit http://www.gastrojournal.org

Contact: Kimberly Wise
media@gastro.org
301-941-2620
American Gastroenterological Association
http://www.gastro.org

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