Aspirin, often used to help prevent heart attacks and strokes, also appears to reduce the risk of the most common type of breast cancer— that is, tumors whose growth was fueled by estrogen or progesterone. Approximately 70% of women with breast cancer have the hormone receptor-positive type.
The women who used aspirin at least four times a week for at least three months were almost 30% less likely to develop hormone-related breast cancer than women who used no aspirin. Aspirin had no effect on the risk for hormone receptor-negative tumors.
Researchers believe that aspirin works by interfering with the body’s production of estrogen.
Many studies have relied on subjects’ recollections of how often they took aspirin. A more rigorous study has linked the use of low-dose aspirin and a reduced risk of growths that can eventually turn into colon cancer. That study involved randomly assigning patients to take aspirin or placebos, the gold-standard method.
For now, it is not recommended that all women take aspirin, because it can cause side effects such as stomach bleeding. Although the findings are exciting, more research is needed before doctors recommend aspirin to prevent breast cancer.