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TUESDAY, Jan. 6 (HealthDayNews) -- Could people who take aspirin for prolonged periods be putting themselves at greater risk of pancreatic cancer?

Maybe so, says a new study asking that question of more than 88,000 nurses. Aspirin has long been thought to suppress tumors of the digestive tract and other organs. And recent research has found no evidence that aspirin users are more likely to suffer pancreatic cancer, even offering hints the drug may protect the insulin-secreting gland from tumors.

But the latest work suggests that people who take the drug consistently over a period of decades have a nearly 60 percent higher risk of developing pancreatic cancer than those who take aspirin less regularly.

"It seems to be consistent use that counts," says study leader Dr. Eva S. Schernhammer, a cancer researcher at Harvard Medical School in Boston. She is quick to caution that while the study is the largest of its kind to date, it turned up only 161 cases of pancreatic cancer among the entire pool of volunteers over an 18-year period.

"There is not much data available to investigate such associations," says Schernhammer, whose findings appear in the Jan. 7 issue of the Journal of the National Cancer Institute.

Although the evidence is murky, the researchers say their study suggests women who took more aspirin each week over time increased their odds of developing pancreatic cancer. However, that trend couldn't be confirmed with statistical certainty.

The line from aspirin to pancreatic cancer, if it exists, may run through obesity. Not only were obese women more likely than their thinner peers to develop the cancer while taking aspirin, but the heavier they were, the greater their risk, Schernhammer says. "We did see that the effects in the overall cohort seemed to be restricted to women who were more obese," she says. Previous research has linked obesity with pancreatic tumors.

Millions of Americans take low doses of aspirin every day to prevent heart attacks and strokes, problems that kill far more people each year than pancreatic cancer. "Overall, the prevalence of cardiovascular disease is so much higher than the prevalence of pancreatic cancer that the benefits would probably still outweigh the risk," Schernhammer says.

Dr. John Baron, an epidemiologist at Dartmouth Medical School and author of an editorial accompanying the journal article, calls the findings "provocative" and says they should force doctors "to think carefully about the actions of aspirin and other [non-steroidal anti-inflammatory drugs] and the mechanisms underlying pancreatic cancer."

But Baron says the results may be misleading. The research seems to suggest that, at least in some cases, pancreatic tumors triggered aspirin use and not the other way around.

Kirsten Moysich, an epidemiologist at the Roswell Park Cancer Institute in Buffalo, N.Y., has looked at aspirin and various cancers, including pancreatic tumors (she found no harm or benefit). In general, Moysich says, the drug appears to protect against cancers, most notably in the colon and rectum, and possibly the lung and breast.

However, she says, contrary evidence "shouldn't be ignored. We cannot make global public health recommendation about regular aspirin use if we don't know the whole picture." And while aspirin "seems to be a wonderful drug," it does have known side effects, including a propensity to cause potentially serious gastric bleeding.

More than 29,000 Americans will be diagnosed with pancreatic cancer this year, according to the National Cancer Institute. The disease is the nation's fifth leading cancer killer, behind tumors of the lung, breast, colon and rectum, and prostate gland.

More information

For more on pancreatic cancer, check out Pancreatica or the National Cancer Institute.

(SOURCES: Eva S. Schernhammer, M.D., Dr.P.H., instructor, Brigham and Women's Hospital, Harvard Medical School, Boston; Kirsten Moysich, Ph.D. associate professor, Roswell Park Cancer Institute, Buffalo, N.Y.; Jan. 7, 2004, Journal of the National Cancer Institute)

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