Women who take aspirin regularly should not panic about a recent study that suggests long-term use could increase the risk of pancreatic cancer, the study's author and other experts say.

The findings would need to be confirmed by other large, well-designed trials before doctors would consider changing recommendations for aspirin use, said lead researcher Eva Schernhammer, MD, of Harvard University Medical School. "No decisions have ever been based on a single study," she noted.

Even if these results are confirmed, it might not affect recommendations for aspirin use because aspirin has health benefits that may outweigh the risk of pancreatic cancer, said Rick Alteri, MD, a medical editor with the American Cancer Society.

Millions of women (and men) in the United States take aspirin daily because it has been proven to reduce the risk of heart disease, the leading killer of American women. Studies also suggest that regular aspirin use may reduce the risk of colorectal cancer, the third most common cancer in the US, although there are currently no recommendations to take aspirin for this purpose.

Schernhammer's study examined aspirin use among more than 88,000 women who were taking part in the Nurses' Health Study, a long-term investigation of risk factors for disease in women. It was presented at a meeting of the American Association for Cancer Research; it has not yet been published in a peer-reviewed journal.

Schernhammer and her colleagues found that women who took at least two regular aspirin tablets per week increased their risk of developing pancreatic cancer. The risk rose as women took more aspirins per week, and if they used aspirin over longer periods of time. Over 18 years of follow-up, 161 women in the study developed cancer of the pancreas.

This isn't the first study to examine the relationship between aspirin and pancreatic cancer. Some research has suggested aspirin could raise the risk. But just last year, data from the Iowa Women's Health Study, another large long-term trial, suggested aspirin actually protects against this disease.

Schernhammer said she and her colleagues had expected to confirm the findings of the Iowa study, and were surprised to get a different result. She noted, though, that the Iowa study did not assess aspirin use as thoroughly as her study did.

"You can't compare the two studies, so we need more studies to compare associations, and those studies would need to have similarly detailed information about aspirin use," she said.

In the meantime, should women stop taking aspirin?

"No, definitely no, for many reasons," Schernhammer said. For one thing, "the evidence just isn't strong enough," she noted.

But more importantly, she said, aspirin has many benefits for preventing other diseases that are much more common than pancreatic cancer.

Heart disease, for instance, affects one out of every five men and women in the United States, according to the American Heart Association. In 2000, more than 500,000 women and more than 440,000 men died from some form of heart disease. Colon cancer strikes more than 105,000 people each year, and kills about 57,000.

About 30,700 Americans get pancreatic cancer each year, and about 30,000 die from it. The average woman's lifetime risk of developing this disease is relatively low, about 1.24%. In this study, taking at least two aspirins daily over 20 years raised that risk by 58%. But even if this finding is confirmed, a woman's overall risk would still be less than 2%. Other risk factors, like smoking and obesity, are far more dangerous.

Women who are concerned about pancreatic cancer should speak to their doctors before they consider giving up aspirin, especially if they are taking it to treat or prevent heart disease or some other condition, said Alteri. Giving up cigarettes, eating right, and exercising are more practical steps women can take to reduce their chances of developing pancreatic cancer, Schernhammer said.