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Study supports role of aspirin in reducing
risk of colorectal cancer
More research needed to identify
those for whom benefit could outweigh risk of side effects
BOSTON - February 2, 2004 - A new study has found that regular
intake of aspirin does appear to be associated with a reduced risk
of the type of colon polyps that can develop into cancer. However,
since risk reduction was strongest with aspirin doses higher than
those used to prevent cardiovascular disease, the researchers say
further study is needed to determine for whom the benefits of such
treatment would outweigh any potential risks. The report - from
researchers at Massachusetts General Hospital (MGH), Brigham and
Women's Hospital and Dana-Farber Cancer Institute - appears in the
February issue of Annals
of Internal Medicine.
"We would love to have a simple, daily tablet that could reduce
the risk of colorectal cancer for everyone, but right now we don't
have that," says Andrew Chan, MD, of the MGH Gastrointestinal
Unit, the paper's lead author. "However, confirming that aspirin,
especially at higher doses, may reduce cancer risk is very exciting
and opens many avenues of research for better understanding the
mechanism of this disease."
Earlier studies at a number of centers suggested that aspirin could
reduce the risk of colorectal polyps but had not established the
most effective dose. The current investigation is part of the Nurses'
Health Study, which has followed more than 120,000 female registered
nurses since the mid-1970s, asking them to complete a questionnaire
on risk factors for cancer and cardiovascular disease every two
years. In 1980, assessments of diet, aspirin use, and colon examination
were added to the NHS questionnaire.
The report in Annals examines data from about 27,000 Nurses
Health Study participants, ages 34 to 77 with no history of cancer,
who reported having endoscopic colon examinations between 1980 and
1998. Among that study group, almost 1,400 participants were diagnosed
with adenoma - a type of colorectal polyp that may develop into
cancer - during the 18-year period.
Participants who reported taking aspirin regularly had a 25 percent
lower risk of adenoma than did women who took no aspirin, with the
lowest risk seen among those who took more than two standard aspirin
tablets per day. Current guidelines for heart disease prevention
suggest that low doses - one baby aspirin tablet per day - are as
effective as higher doses. The authors caution that high doses of
aspirin have been shown to pose a greater risk of side effects such
as bleeding.
"Before these findings can be translated into clinical recommendation,
we need better ways of identifying exactly who should take aspirin
to reduce colorectal cancer risk," says Chan, a research fellow
at Harvard Medical School. "Other potential risk factors or
genetic markers could be associated with levels of benefit that
might outweigh the risks posed by higher doses of aspirin. Until
those questions are answered, people should follow current screening
recommendations, which are proven to save lives."
Additional authors of the study are Charles Fuchs, MD, MPH, senior
author, of Dana-Farber Cancer Institute and Brigham and Women's
Hospital (BWH); Edward Giovannucci, MD, ScD, Eva Schernhammer, MD,
DrPH, Graham Colditz, MD, DrPH, and David Hunter, MD, ScD, all of
BWH and the Channing Laboratory at Harvard Medical School; and Walter
Willett, MD, DrPH, of BWH and Harvard School of Public Health. The
research was supported by grants from the National Institutes of
Health.
The Nurses' Health Study (NHS) was initiated in 1976 at BWH. The
NHS is the longest-running, major women's health study ever undertaken
and has resulted in hundreds of journal articles, many containing
groundbreaking findings on how to prevent some of the major causes
of disease and death in women.
Massachusetts General Hospital, established in 1811, is the original
and largest teaching hospital of Harvard Medical School. The MGH
conducts the largest hospital-based research program in the United
States, with an annual research budget of more than $350 million
and major research centers in AIDS, cardiovascular research, cancer,
cutaneous biology, medical imaging, neurodegenerative disorders,
transplantation biology and photomedicine. In 1994, MGH and BWH
joined to form Partners HealthCare System, an integrated health
care delivery system comprising the two academic medical centers,
specialty and community hospitals, a network of physician groups,
and nonacute and home health services.
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Media Contact: Sue
McGreevey, MGH Public Affairs
Physician Referral Service: 1-800-388-4644
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