News Release

Aspirin use may increase pancreatic cancer risk

Peer-Reviewed Publication

American Association for Cancer Research

PHOENIX – The many health benefits of regular aspirin use have been well-documented, and include the prevention of certain cancers, heart attacks and strokes, as well as dementia, Alzheimer's disease and cataracts. But a new study advises women that aspirin may not always be helpful. According to research presented today at the American Association for Cancer Research Second Annual International Conference on Frontiers in Cancer Prevention Research, extended regular use of aspirin may be associated with a significantly increased risk of pancreatic cancer among women.

Researchers examined the relationship between aspirin use and the development of pancreatic cancer among the participants in the Nurses' Health Study. Among the 88,378 women who were initially cancer-free, 161 cases of pancreatic cancer were documented during 18 years of follow up. Aspirin use was first assessed at baseline in 1980, and updated biennially thereafter. Participants were classified according to a history of aspirin use.

A long duration of regular aspirin use (two or more tablets per week) was associated with a significant increase in pancreatic cancer risk; women who reported 20 or more years of regular aspirin use experienced a 58 percent increased risk (a relative risk of 1.58). The relative risk (RR) is the risk of developing the disease in the treated group compared to the risk in the control group.

Among women who reported aspirin use on at least two of three consecutive biennial questionnaires (compared to consistent non-users), the risk of developing pancreatic cancer was increased by nearly 86 percent for women taking 14 or more tablets per week (RR 1.86). The risk was increased by 41 percent for those taking six to 13 tablets per week (RR 1.41), 29 percent for those taking four to six per week (RR 1.29), and 11 percent for those taking one to three per week (RR 1.11). The results suggest that extended aspirin use may be associated with significantly increased pancreatic cancer risk among women.

"These findings, if confirmed, add another variable to the complex risk-benefit profile of aspirin," said Eva Schernhammer, M.D., of Brigham and Women's Hospital and Harvard University Medical School, and lead investigator of the study.

"Women need to discuss their situation with their doctor before making any decisions on their own about the use of aspirin," she added. The Nurses' Health Study, initiated in 1976 at Brigham and Women's Hospital, is the longest-running major women's health study ever undertaken. Study findings have resulted in hundreds of journal articles, many containing groundbreaking research on how to prevent some of the major causes of disease and death in women.

In vitro experiments and limited animal studies have suggested that aspirin and non-steroidal anti-inflammatory drugs (NSAIDS) may inhibit pancreatic cancer; but few studies have examined the association between aspirin use and pancreatic cancer in humans and these results have been inconsistent.

The American Cancer Society estimates that in 2003, about 30,700 people in the United States will be diagnosed with pancreatic cancer and about 30,000 will die of the disease. Pancreatic cancer is the fourth leading cause of death from cancer. About two out of 10 patients live at least one year after the cancer is found, but very few survive for five years.

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Founded in 1907, the American Association for Cancer Research is a professional society of more than 21,000 laboratory, translational, and clinical scientists engaged in cancer research in the United States and in more than 60 other countries. AACR's mission is to accelerate the prevention and cure of cancer through research, education, communication, and advocacy. Its principal activities include the publication of five major peer-reviewed scientific journals: Cancer Research; Clinical Cancer Research; Molecular Cancer Therapeutics; Molecular Cancer Research; and Cancer Epidemiology, Biomarkers & Prevention. AACR's annual meetings - next year in Orlando, Fla., March 27-31 - attract more than 15,000 participants who share new and significant discoveries in the cancer field. Specialty meetings like this one, held throughout the year, focus on the latest developments in all areas of cancer research.


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