The study, published online in the Journal of the National Cancer Institute, pooled results from existing randomized trials of daily aspirin for prevention of vascular events and found daily aspirin use was associated with an estimated 16 percent lower overall risk of cancer mortality.
Study leader Eric J. Jacobs of the American Cancer Society and colleagues analyzed data from 100,139 U.S. adults age 60 and older -- mainly white -- who were tracked for up to 11 years.
The reduction in cancer mortality observed in the current study was considerably smaller than the 37 percent reduction reported in a recent pooled analysis of randomized trials, Jacobs said.
Jacobs and colleagues said their study was observational, not randomized, and therefore could have underestimated or overestimated potential effects on cancer mortality if participants who took aspirin daily had different underlying risk factors for fatal cancer than those who did not.
However, the study's large size is a strength in determining the extent aspirin use might lower cancer mortality, Jacobs said.
"Although recent evidence about aspirin use and cancer is encouraging, it is still premature to recommend people start taking aspirin specifically to prevent cancer," Jacobs said in a statement. "Any decision about daily aspirin use should be made only in consultation with a healthcare professional."