A large study found that taking aspirin daily may reduce the risk of estrogen-receptor-positive breast cancer by about 16%.
Most breast cancers -- about 75% -- are hormone-receptor-positive. In this study, taking aspirin every day DIDN'T lower the risk of hormone-receptor-negative breast cancer. Also, taking aspirin less than daily didn't reduce the risk of breast cancer.
The more than 126,000 women who were part of this study completed a questionnaire on how often they took aspirin. About 22,000 women (18%) were taking aspirin daily at the start of the study. The women were followed for 7 years.
Aspirin is a nonsteroidal anti-inflammatory medicine (NSAID, pronounced EN-sed). Because NSAIDs reduce inflammation, researchers thought that NSAIDs also might be able to reduce cancer risk, including breast cancer risk. Like this study, other research has looked at whether taking aspirin every day can lower cancer risk, including breast cancer risk. But the results have been mixed. Some studies (but not all) suggest that aspirin might lower the risk of certain cancers, including colon, prostate, and breast. This is the first time researchers looked at aspirin's effects on different types of breast cancer, rather than overall breast cancer risk.
Aspirin treats pain, inflammation, and fever. Many adults take a low dose of aspirin every day to lower the risk of a heart attack or stroke. Still, daily aspirin isn't right for everyone. While the results of this study are promising, there are some important things to keep in mind:
All the women in this study who took aspirin every day took different doses. So it's not clear how much daily aspirin is best to lower breast cancer risk. Most adults take between 325 and 650 milligrams of aspirin for pain or inflammation, sometimes several times a day. But people who take daily aspirin to benefit their hearts usually take a lower dose, about 81 milligrams per day. Other research suggested that this lower dose didn't reduce cancer risk.
The decrease in breast cancer risk for women who took daily aspirin was relatively small (16%). Like any medicine, aspirin has risks as well as benefits. The side effects of aspirin include bleeding, bruising, stomach upset and ulcers, and allergic reactions.
More research is needed before doctors can decide that daily aspirin can safely lower breast cancer risk.
While the results of this study offer hope, don't take aspirin every day unless you talk to your doctor first. For more information on how you can safely lower your breast cancer risk, visit the breastcancer.org Lower Your Risk section.