One suggests the drug may lower the risk of dying from prostate cancer. The other sees no significant drop in the risk for developing breast cancer.
Both studies are published online in the Journal of Clinical Oncology.
Men treated for prostate cancer who took aspirin for other conditions were less likely to die of their cancer than those not taking aspirin.
The other saw no significant drop in the risk for developing breast cancer.
But researchers point out these were different types of studies and neither proved a cause-and-effect relationship between aspirin use and its effect on cancer.