Estimates of benefits and harms of prophylactic use of aspirin in the general population.


The balance of benefits and harms from aspirin use in the general population are still unclear. In particular, the harmful adverse effects of aspirin have not been quantified. In addition, the optimal dose of aspirin and required duration of use remain to be determined. To better understand the benefits and harms of aspirin use, the authors reviewed recent studies on aspirin use and its cancer and cardiovascular prevention benefits as well as the harms.


The authors synthesized information from six recent systematic reviews that reported on the use of aspirin for prevention of heart attacks, strokes and cancer. These reviews had included a broad range of research designs, including case-control studies, observation of populations, and clinical trials. The study focused on quantifying the benefits and harms of aspirin use by age and gender using a series of statistical models. In addition, they distinguished between the occurrence of events and mortality from these events for both harms and benefits.


  • Aspirin reduces the occurrence of cancer by 7% in women and 9% in men. Reduction in the risk of cancer was seen for the following cancer sites: colon/rectum, breast, lung, prostate, stomach, and esophagus.

  • Aspirin reduces mortality from cancer by 9% in women and 12% in men.

  • The harms of aspirin use, including bleeding events, increase with age. Excess deaths among aspirin users become prominent only after 65 years.

  • To reduce cancer occurrence, a minimum of 3 years of aspirin use is required, but to prevent cancer deaths, 5 years of aspirin use appears to be necessary. The cancer prevention benefits of aspirin appear to last several years after aspirin is stopped.

  • In both men and women from ages 50 to 65 years, the analysis show that ten years of aspirin use has substantial net benefits; that is, the benefits of aspirin are much greater than its harms.

  • Reduced cancer occurrence and cancer death are seen for all daily aspirin doses above 75 mg with no signs that benefits are greater for higher doses.

  • GI bleeding with aspirin can be reduced with the use of proton pump inhibitors as well as screening and treatment for H. pylori stomach infection.


  • Aspirin has extensive benefits in preventing cancer across a broad range of cancer sites. Aspirin use reduces both the occurrence of cancer and death from cancer. The cancer prevention benefit of aspirin is greater than aspirin’s heart disease and stroke benefits.

  • Low doses (75 mg or 81 mg) are adequate for both the cardiovascular and cancer benefits of aspirin.

  • The benefits of aspirin appear to outweigh its harms in men and women starting aspirin between 50 and 65 years of age. Excess bleeding, as one of the most prominent harm from aspirin, increases with age. The benefit of using aspirin for people older than 65-75 years is not clear because the harms of excess bleeding may offset any benefits.

  • Strategies to protect the stomach from damage due to aspirin may make aspirin beneficial, even in older patients.