Aspirin’s Ability to Prevent Cancer Gets Attention of American Cancer Society
‘Exciting opportunity to reconsider the potential role of aspirin in cancer prevention’
April 12, 2012—A new report by American Cancer Society scientists says new data showing aspirin's potential role in
reducing the risk of cancer death bring us considerably closer to the time when cancer prevention can be included in clinical guidelines for
the use of aspirin in preventative care.
The report, published early online in Nature Reviews Clinical Oncology, says even a 10% reduction in overall
cancer incidence beginning during the first 10 years of treatment could tip the balance of benefits and risks favorably in average-risk
Current guidelines for the use of aspirin in disease prevention consider only its cardiovascular benefits, weighed
against the potential harm from aspirin-induced bleeding. While daily aspirin use has also been convincingly shown to reduce the risk of
colorectal cancer and recurrence of adenomatous polyps, these benefits alone do not outweigh harms from aspirin-induced bleeding in
But recently published secondary analyses of cardiovascular trials have provided the first randomized evidence that daily
aspirin use may also reduce the incidence of all cancers combined, even at low doses (75-100 mg daily).
The current review, led by Michael J. Thun, M.D., vice president emeritus of epidemiology and surveillance research for
the American Cancer Society was not designed as a comprehensive review of the literature, but instead is a focused discussion of the key
outstanding issues in using aspirin as a cancer prevention tool.
The report says recently published meta-analyses of results from randomized trials of daily aspirin treatment to prevent
vascular events have provided provocative evidence that daily aspirin at doses of 75 mg and above might lower both overall cancer incidence
and overall cancer mortality.
Why don't more women take a daily aspirin to prevent heart
Heart disease is the leading cause of death among
women, and evidence-based national guidelines promote the use of daily aspirin for women at increased risk for cardiovascular disease.
However, less than half of the women who could benefit from aspirin are taking it.
"Based on this survey, it is evident that the majority
of women for whom aspirin is recommended for prevention of cardiovascular disease are not following national guidelines," says
Editor-in-Chief Susan G. Kornstein, MD, Director of the Virginia Commonwealth University Institute for Women's Health, Richmond, VA.
In six primary prevention trials of daily low-dose aspirin, randomization to aspirin treatment was associated with an
approximately 20% reduction in overall cancer incidence between 3 and 5 years after initiation of the intervention and a 30% reduction during
follow up more than 5 years after randomization.
Cancer mortality was also reduced during study follow up that happened more than 5 years after the start of aspirin use
in analyses that included 34 trials of daily aspirin at various doses.
Surprisingly, the size of the observed benefit did not increase with daily doses of aspirin above 75-100 mg. Notably,
these meta-analyses excluded results from the Women's Health Study (WHS), a large 10-year-long trial of 100 mg of aspirin taken every other
day, which reported no reduction in cancer incidence or mortality.
"The accumulating data from randomized clinical trials provide an exciting opportunity to reconsider the potential role
of aspirin in cancer prevention," write the authors. They say several important questions remain unanswered, such as the exact magnitude of
the overall cancer benefit and which individual cancer sites contribute to this benefit.
"However, these new data bring us considerably closer to the time when cancer prevention can be integrated into the
clinical guidelines for prophylactic treatment following regulatory review by the FDA and the European Medicines Agency."