Jan. 6, 2004 -- Regular use of aspirin for 20 years or more may increase the risk of pancreatic cancer among women, a new study suggests.
The unexpected finding is based on data from more than 88,000 nurses followed for 18 years in the Nurses' Health Study.
Only 161 of these women developed pancreatic cancer, which is nearly always fatal within five years. But women who regularly took aspirin for more than 20 years were more likely to be among this number. The more standard aspirin tablets (325 mg) a woman took, the higher her risk compared with women who did not use aspirin:
- Risk increased by 86% for women who took 14 or more tablets a week.
- Risk increased by 41% for women who took six to 13 tablets a week.
- Risk increased by 29% for women who took four to six tablets a week.
- Risk increased by 11% for women who took one to three tablets a week.
The findings appear in the Jan. 7 issue of the Journal of the National Cancer Institute.
Aspirin: A Two-Edged Sword
Despite this increased risk, researcher Eva Schernhammer, MD, PhD, of Harvard Medical School notes that regular aspirin use decreases risk of colon cancer. And it also cuts the risk of heart disease. Both of these diseases are deadly -- and a lot more common than pancreatic cancer.
"Clearly the benefits of aspirin are still here and will not be outweighed by our research," Schernhammer told WebMD in an interview in October 2003 when the results were presented at a cancer research conference. "We need further studies to confirm these findings -- only then can we start thinking of this as a real issue for women."
Aspirin -- and other anti-inflammatory pain relievers -- inhibit an enzyme called cyclooxygenase. It's similar to another enzyme called lipoxygenase. Some kinds of lipoxygenase fight cancer. Other kinds help it along. It might be that aspirin inhibits this compound. That, Schernhammer says, might mean aspirin fights cancer in some parts of the body and speeds its growth in other parts.
How to Lower Your Risk
If you're worried about pancreatic cancer, researchers say there are more effective things you can do than quit using aspirin.
"First of all, I advise women to talk with their doctors if they are worried," Schernhammer says. "But you can take many measures to prevent pancreatic cancer. That could be to quit smoking -- smoking is associated with pancreatic cancer. Reduce body weight. And also change some dietary habits. Food with high glycemic load increases pancreatic cancer risk. These are steps a woman can take today. As far as aspirin goes, you should talk with your doctor and see if the risk outweighs the benefits."
More Research Needed How to Lower Your Risk
In an editorial that accompanies the study, John Baron, MD, of Dartmouth Medical School, says much more research is needed before any link between aspirin and pancreatic cancer can be firmly established.
There are no easy answers to the question of what aspirin and other anti-inflammatory drugs do to the development of pancreatic cancer, writes Baron.
"Fortunately, conflicting data from diverse threads of research are often a very effective push toward scientific progress," says Baron.
With reporting by Dan DeNoon.