The benefits of low dose aspirin in decreasing cardiovascular events such as stroke and heart attack are well described. In 2009 the U.S Preventative Task Force made the following statement:
- Men age 45 to 79 years should use aspirin when the potential benefit of a reduction in myocardial infarctions outweighs the potential harm of an increase in gastrointestinal hemorrhage.
- Women age 55 to 79 years should use aspirin when the potential benefit of a reduction in ischemic strokes outweighs the potential harm of an increase in gastrointestinal hemorrhage.
- Evidence is insufficient to assess the balance of benefits and harms of aspirin for cardiovascular disease prevention in men and women 80 years or older.
- Do not encourage aspirin use for cardiovascular disease prevention in women younger than 55 years and in men younger than 45 years
But after a recent study in the Lancet, future evidence-based guidelines for aspirin prevention must consider the use of aspirin for cancer prevention in addition to the prevention of vascular disease.
The study suggests that in addition to the known cardiovascular benefits and long term reduction of death due to cancer, daily low dose aspirin may reduce cancer incidence and mortality in the short term. In addition, the study suggests that there is a decrease in risk of major bleeding outside of the brain with extended use. Here are the salient points:
- Prior to the study, the short-term effect of aspirin on cancer was less certain, especially in women, and the effects on cancer incidence were largely unknown.
- Daily aspirin at any dose reduces the risk of colorectal cancer by 24% and associated mortality by 35% after a delay of 8-10 years
- The new study shows a 21% reduced risk of cancer death with benefit apparent after 5 years, with reduced mortality due to several cancers (including breast) for 20 years
- There is a suggestion that some of aspirin’s preventive effect occurs early in the development of cancer
- Aspirin might also have an effect on the growth and spread of established tumors as well as their initiation
- Extended use of aspirin is likely safer than previously supposed and will be of value in prevention of cancer
The authors conclude that alongside the previously reported reductions in cancer deaths, there is an overall benefit from aspirin in the shorter-term, and increased risk of major extracranial bleeding does not persist with extended use of aspirin. These findings add to the case for long-term use of aspirin for cancer prevention in middle age, in conjunction with appropriate dietary and lifestyle interventions.
Additional studies will be needed to more specifically identify what dose of aspirin and in which people the benefits will be most significant. But for now, I am comfortable recommending a baby aspirin a day for women beginning perhaps as early as age 45, but certainly at 55 for the cancer prevention benefits that aspirin has been shown to provide.