Low-Dose Aspirin Reduces Recurrence of Colorectal Polyps

Hanover, NH- When it comes to colorectal cancer, a baby aspirin a day may keep the doctor away, according to Norris Cotton Cancer Center researchers, who presented results of their study at the 93rd Annual Meeting of the American Association for Cancer Research in San Francisco.

Dartmouth Medical School investigators tested two different doses of aspirin for their ability to prevent the recurrence of polyps, also called colorectal adenomas, which are benign tumors that may progress to cancer. They found modest preventive benefit with both regimens, but a higher reduction in risk with the lower dose of 80 mg per day � one baby aspirin.

"This is the first clinical trial focused on the protective effects of aspirin against the development of tumors in the large bowel," said John A. Baron, MD, professor of medicine at Dartmouth Medical School, who led the team. "We were surprised to find that the lower dose showed more effect." Colorectal cancer is the second leading cause of cancer death, and is likely to kill more than 56,000 Americans this year.

Compared with the placebo group, patients taking 80 mg per day reduced their risk of recurrent adenomas by 19%, while those taking 325 mg (one standard aspirin) had a 4% reduction in risk. When the data were analyzed looking at the more aggressive types of adenomas (tubulovillous or villous) that were initially removed, risk reductions were 40% with the low-dose regimen and 19% with the high dose.

Patients were eligible for the study if they had at least one adenoma removed within the preceding three months, had no known cardiovascular disease or other conditions usually treated with aspirin (e.g., long-standing arthritis, headaches) and had no hereditary cancer syndromes. Potential study participants took 325 mg of aspirin daily for three months to identify anyone who had problems with the highest protocol dose or with compliance. Afterward, 1,121 patients were randomly assigned to one of three groups: placebo, 80 mg of aspirin per day, or 325 mg of aspirin per day for an average length of 34 months.

"These two doses were tested because they reflect amounts often used for heart disease prevention, and we wanted to be consistent in our study to avoid the possibility of conflicting recommendations for these two health issues at a future date," explained Baron.

The Dartmouth investigators will continue to follow these patients in an observational study design to track aspirin use, which is now optional for all three study groups, and to monitor for recurrent adenomas and development of colorectal cancer. The studies are part of the Cancer Center's polyp prevention group.

For more information contact Mary Hawkins at 603-650-0849. More information about cancer and treatments is available through the Norris Cotton Cancer Center.

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