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University of Iowa News Release

March 6, 2003

UI Contributed To Study On Aspirin

A seven-year study led by Dartmouth Medical School researchers shows that a daily dose of aspirin can be effective in reducing the risk of colon adenomas -- benign tumors, or polyps -- in people who previously have had the polyps. These benign tumors can develop into cancer if left in the bowel. University of Iowa researchers contributed to the finding, which will appear in the March 6 issue of the New England Journal of Medicine.

John Baron, M.D., a physician and researcher with the Norris Cotton Cancer Center at Dartmouth-Medical Center, was lead author of the article. The UI-led portion involved 150 participants at five sites in Iowa and Illinois: Gastroenterologists P.C. of Cedar Rapids; Gastroenterology Associates of Iowa City; Gastroenterology Consultants of Moline; Internists P.C. of Cedar Rapids (Nile Dusdieker, M.D.); and the Center for Digestive Diseases in the department of internal medicine at UI Hospitals and Clinics.

The findings in this first clinical study confirm previous epidemiological studies (based on observation) that showed that the recurrence of colon cancer is lower in people who take aspirin than in those who do not, said Robert Summers, M.D., UI professor of internal medicine and lead investigator for the Iowa-based portion of the study. Robin Thompson, UI clinical research coordinator in internal medicine, assisted with the study.

"This is the first time where we gave aspirin in a controlled fashion to people who have a high risk of recurrent polyps to see if the aspirin reduced that recurrence," Summers said. "The benefit is modest, but I think we can encourage people who are at a higher risk, either because of previous polyps or a family history of colon cancer, that taking aspirin is beneficial."

The multicenter, randomized, double-blind study -- meaning neither the researchers nor the participants knew who received aspirin and who received placebo (inactive substance) -- looked at more than 1,100 patients previously diagnosed with colorectal adenomas. Some patients received aspirin in either an 81 mg or a 325 mg dose while other participants received the placebo.

The investigators found that the group receiving the smaller dose of aspirin -- 81 mg, or the equivalent of one baby aspirin -- had a lower incidence of recurring polyps than did those treated with the larger 325 mg dose of aspirin. Overall, those treated with a daily dose of baby aspirin found their risk of polyps reduced by 19 percent and their risk of advanced lesions reduced by more than 40 percent. These larger advanced polyps are the ones that are most likely to develop into colon cancer.

Summers said it is not exactly clear why the smaller dosage offered greater benefits. However, he said an advantage of the lower dose may be a lower incidence of adverse side effects.

"Very few problems were associated with taking this 81 mg dose," Summers said. "Taking aspirin has the potential of increasing the risk of developing ulcers or bleeding, but it is not a major problem at this low dose."

Both Baron and Summers emphasized that although aspirin generally is a safe drug, people should check with their physicians before beginning to take aspirin daily to ward off polyps.

Baron co-authored another report in the journal that found aspirin also can protect people who already have had colorectal cancer, as opposed to the benign tumors. In that Dartmouth companion study on patients with a history of colon or rectal cancer, participants took either a regular aspirin (325 mg) or placebo. That study found that aspirin reduce the recurrence of polyps by about 35 percent.

Previous research by UI investigators showed that calcium supplements can also reduce the risk of recurrent polyps by about 20 percent in people who have had the benign tumors.

"A nice thing about these agents -- aspirin and calcium -- is that they both have some benefit for other medical problems. Aspirin has been shown to reduce the risk of heart attacks, and calcium is helpful in preventing osteoporosis," Summers said.

Some patients who participated in the Iowa-led portion of the study will continue to participate in an extension study related to colon cancer.

As with all medical treatment, it is best to consult with your personal physicians before making any changes to your health care routine.

STORY SOURCE: University of Iowa Health Science Relations, 5137 Westlawn, Iowa City, Iowa 52242-1178

CONTACT: Media: Becky Soglin, (319) 335-6660 <>

OTHER INFORMATION: This release includes information provided by Dartmouth Medical School. For a copy of the journal article mentioned in the release or interviews with the lead researcher, Dr. John Baron, contact Deborah Kimbell at (603) 653-1913.


UI Contributed To Study On Aspirin Preventing Pre-cancerous Polyps

UI researchers contributed to a study that found that a daily dose of aspirin can be effective in reducing the risk of colon adenomas -- benign tumors -- in people who have had these precancerous polyps. The finding appears in the March 6 issue of the New England Journal of Medicine.


University of Iowa Health Care describes the partnership between the UI Roy J. and Lucille A. Carver College of Medicine and UI Hospitals and Clinics and the patient care, medical education and research programs and services they provide. Visit UI Health Care online at

STORY SOURCE: University of Iowa Health Science Relations, 5137 Westlawn, Iowa City, Iowa 5224-1178

CONTACTS: (media) Becky Soglin, 319 335-6660