General Information

There is growing interest in the potential role of aspirin in reducing the risk of cancer or improving survival after diagnosis, though observational studies demonstrate mixed results.

An analysis of 135,965 men and women from the Nurses’ Health Study and Health Professionals Follow-up Study, found, for example, a significant decrease in risk for overall cancer with regular aspirin use (relative risk [RR], 0.97; 95% CI, 0.94-0.99), which was defined as 0.5 to 1.5 standard tablets per week for at least 6 years.1 The drivers of this association were gastrointestinal tract and colorectal cancers.

Aspirin use and cancer has primarily been evaluated by observational studies, which may have substantial bias. Several randomized controlled trials, however, are ongoing, including ASPIRED ( Identifier: NCT02394769) and ADD-ASPIRIN ( Identifier: NCT02804815).2,3

The following is a set of recent trials on the relationship between aspirin-use and cancer and their findings.

Colorectal Cancer

The United States Preventative Services Task Force (USPSTF) has published recommendations on aspirin use for the reduction of risk of colorectal cancer (CRC). According to their recommendation, the risk reduction occurs after 5 to 10 years of use and is therefore suggested for use among patients age 50 to 59. Though a dose for CRC risk reduction is not specified, the USPSTF recommends 81 mg for cardiovascular disease risk reduction. 4

The USPSTF recommendations are based on a systematic review demonstrating that at least 75 mg of aspirin daily or every other day significantly reduced the risk of all-cause mortality in 10 years (RR, 0.94; 95% CI, 0.89-0.99) and reduced the risk of CRC mortality by 33% during over a 20-year period. The incidence of CRC was reduced by 40% after 10 years of use (RR, 0.60; 95% CI, 0.47-0.76). 5

An observational study demonstrated significantly improved overall survival (OS; hazard ratio [HR], 0.41; 95% CI, 0.37-0.47) with aspirin, but not other thrombocyte aggregation inhibitors, among patients with CRC.6

A meta-analysis of observational studies found that post-diagnosis aspirin use was significantly associated with improved OS with CRC (HR, 0.78; 95% CI, 0.64-0.96), but not CRC-specific mortality or pre-diagnosis aspirin use.7