Aspirin Raises Pancreatic Cancer Risk

But Overall Health Benefits of Aspirin Outweigh Small Increase in Deadly Cancer

From the WebMD Archives

Oct. 27, 2003 -- Regular aspirin use lowers risk of heart disease and some cancers. But there may be a cost to that benefit: A small increase in risk of pancreatic cancer.

The unexpected finding comes in a report to this week's Frontiers in Cancer Prevention Research meeting, sponsored by the American Association for Cancer Research. Harvard researcher Eva Schernhammer, MD, and colleagues analyzed 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.

Despite this increased risk, Schernhammer 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 tells WebMD. "We need further studies to confirm these findings -- only then can we start thinking of this as a real issue for women."

Scott Lippman, MD, of the University of Texas M.D. Anderson Cancer Center in Houston, agrees that it's too soon to cut back on aspirin for fear of pancreatic cancer.

"This is really a very provocative and unexpected finding," Lippman said at a news conference held to announce the findings. "One reason why this kind of study is not definitive is because it is hard to control for all the factors that might influence pancreatic cancer. The increased risk could be related to the reason the women were taking aspirin, not to aspirin itself."

Aspirin: A Two-Edged Sword

As in every other study that's looked at the issue, aspirin cut the risk of colon cancer in the Nurses' Health Study. How could aspirin fight one kind of cancer and help another kind?

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.

Another possible explanation is that aspirin and other drugs of its class are linked to pancreatitis -- inflammation of the pancreas. Pancreatitis increases a person's risk of pancreatic cancer.

How to Lower Your Risk

If you're worried about pancreatic cancer, there are a lot 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."

The researchers also collected data on other anti-inflammatory pain relievers. A report on these results is expected soon.

Show Sources

SOURCES: Frontiers in Cancer Prevention Research meeting, American Association for Cancer Research, Phoenix, Oct. 26-30, 2003. News conference, American Association for Cancer Research. Eva Schernhammer, MD, Harvard Medical School, Boston.
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