A drug that lowers cancer and mortality risks in seniors may already be in many medicine cabinets, say scientists from the National Cancer Institute in Rockville, Maryland, and colleagues.

In a large-scale cohort study, aspirin use three times a week or more reduced the risk of all-cause cancer, gastrointestinal cancer, colorectal cancer and cancer mortality. Participants were adults aged 65 years and older. The greatest risk reduction was for colorectal cancer mortality, the investigators reported. 

In some cases, greater body mass index was also tied to greater risk reduction. That’s in contrast to the results of previous studies, which showed that aspirin’s protection is reduced among people with obesity. 

“This study did not find an association of overweight or obesity with decreased efficacy,” the study team wrote in JAMA Network Open

Yet the researchers cautioned that while the evidence for aspirin as a tool in cancer prevention is strong, the bulk of studies suggest that the growing number of people who are overweight and obese may alter its efficacy. This trend “must be considered along with age and risk of bleeding before recommending aspirin for cancer prevention,” they concluded.