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MILWAUKEE - Experts warn not to make too much of it, but a new study casts a small cloud over the sunny expectations about aspirin's ability to prevent heart disease, breast and colon cancer and a host of other maladies.
Women who took aspirin regularly for a long time had higher rates of deadly pancreatic cancer in a study of more than 88,000 nurses by Harvard University researchers.
It's one of very few significantly negative findings in a large body of evidence that suggests aspirin is a cheap, relatively safe way to ward off ailments as diverse as Alzheimer's disease, stroke and cataracts.
Doctors say people should consider their own health risk situation when deciding whether to take aspirin or how much. A daily "baby" aspirin (81 milligrams) has long been recommended for many people to prevent heart disease, which is far more common than pancreatic cancer, they note.
"People should base their decision still on their cardiovascular risk, because that is going to dominate the whole equation," said Michael Thun, the American Cancer Society's chief epidemiologist, who was not involved in the new study but reviewed it for expected publication soon in a scientific journal.
The cancer society is about to publish its own study from its database of 1.2 million people, which found that aspirin didn't make much difference either way on the risk of getting pancreatic cancer, Thun added.
Results of the Harvard study were presented Monday at an American Association for Cancer Research conference in Arizona.
According to the American Cancer Society, pancreatic cancer is the fourth leading cause of cancer deaths. An estimated 30,700 new cases and a nearly equal number of deaths from it are expected in the United States this year. The one-year survival rate is 21 percent, and the five-year rate a mere 4 percent.
Smoking doubles the risk of getting pancreatic cancer, and rates of it are higher in countries with high-fat diets. But little else is known about risk.
Aspirin is a non-steroidal anti-inflammatory drug, or NSAID, a category that includes most over-the-counter pain medications except for acetaminophen (Tylenol). They block a substance called COX-2, which triggers inflammation and is thought to play multiple roles in cancer's formation and spread.
Many studies suggest aspirin can prevent colon and even breast cancer, but studies on pancreatic cancer have had mixed results.
Harvard's Nurses Health Study is the largest and longest-running so far to look at the issue. Researchers found a 58 percent greater risk of pancreatic cancer among women who said they took two or more regular-dose (325-milligram) aspirin pills a week for 20 or more years.
Women who on at least two consecutive questionnaires every two years said they used aspirin had higher risk depending on frequency of use. Risk was 86 percent higher for those taking 14 or more pills per week, 41 percent higher with six to 13 pills, 29 percent higher with four to six pills and 11 percent higher with one to three pills compared with non-aspirin takers.
"The more aspirin a woman took, the higher the risk," said Harvard physician Eva Schernhammer, who led the study, which was funded by the National Cancer Institute.
"The results are extremely provocative and will generate quite a bit of interest," said Scott Lippman, a cancer expert at the University of Texas' M.D. Anderson Cancer Center.
Ernest Hawk, a physician and prevention expert at the National Cancer Institute, called the study "well done" but noted there are limits to what can be concluded from any research that just observes large groups of people. What's needed is a randomized, controlled study in which some people get aspirin and others dummy pills to see what happens when it's tested in the more rigorous manner.
Hawk also said aspirin's benefits against cancer in general are well-founded.
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(c) 2003, Milwaukee Journal Sentinel. Distributed by Knight Ridder/Tribune News Service.
