Researchers found that study participants who reported regular use of Aspirin (at least once weekly) showed a 20% lower incidence of breast cancer. For those participants who took Aspirin more often (daily) had a higher incidence of lessened risk at 28%. Another NSAID, Ibuprofen also appears to lower risk though at a lower percentage than Aspirin. Tylenol (acetaminophen) does not appear to affect breast cancer development.
Experts suspect that Aspirin which is a COX inhibitor treats and controls cancer by stopping angiogenesis, the process by which tumors grow and sustain their own blood vessels ("angio" means vessels, and "genesis" means growth). Angiogenesis is a complex process during which tumors rely on an enzyme called cyclooxygenase-2 (COX-2). They reason that these drugs block this enzyme, preventing the growth of the blood vessels necessary for tumor growth.
Aspirin is not without risk; it can cause ulceration and bleeding of the intestinal tract and may interact with other medications leading to serious health conditions. Check with your doctor before taking this drug.