HealthDay News — Taking low-dose aspirin for years may lower the risk of heart attack, stroke, and colorectal cancer by a small amount in female patients aged less than 65 years, according to a study published in Heart. This benefit, however, is countered by an increase in the risk of major gastrointestinal bleeding.

“The role of aspirin in primary prevention remains unclear, as it is uncertain whether the combined benefits for cancer and cardiovascular disease (CVD) outweigh the increase in major bleeding events,” noted Rob C. M. van Kruijsdijk, MD, of University Medical Center Utrecht, and colleagues.

To identify women who benefit from alternate-day aspirin in regard to cancer, CVD, and major gastrointestinal bleeding outcomes, the investigators conducted a clinical trial involving 27,939 women who were healthy and aged 55 years on average at the start of the study.

The study participants were randomly assigned to take low-dose (100 mg) aspirin or placebo pills every other day. Over 15 years of follow-up, 11% of the patients either developed cancer, suffered heart attack or stroke, or died of cardiovascular causes.

Women who had taken aspirin saw a small reduction in their odds of CVD or colorectal cancer, but at the expense of an increase in the risk of gastrointestinal bleeding, noted the study authors.

For every 133 women on aspirin for 15 years, one would suffer a serious major gastrointestinal bleeding episode. One out of 29 of women would have less serious problems, including a stomach ulcer or slight bleeding in the digestive tract.

By comparison, 709 women would have to take aspirin to prevent one case of colorectal cancer, and 271 would have to regularly take aspirin to ward off a single cardiovascular complication.

“Concurrent evaluation of the absolute effects on cancer, CVD and major gastrointestinal bleeding showed that alternate-day use of low-dose aspirin is ineffective or harmful in the majority of women in primary prevention,” concluded the researchers.


  1. Kruijsdijk RCM et al. Heart. 2014; doi: 10.1136/heartjnl-2014-306342