Aspirin May Protect Against Breast Cancer

May 25, 2004 -- Taking a regular aspirin can lower a woman's risk of breast cancer, a new study shows.

Regular use of the pain reliever ibuprofen was not associated with a significant decrease in the risk of breast cancer. Along with aspirin, ibuprofen belongs to a class of pain relievers called NSAIDs, or non-steroidal anti-inflammatory drugs. The pain reliever acetaminophen, found in Tylenol, is not an NSAID and also did not reduce the risk of breast cancer.

The findings are reported in the May 26 issue of TheJournal of the American Medical Association.

The protective effect of aspirin was seen only in women with hormone receptor-positive breast cancers -- breast cancers that grow in response to hormones. Most breast cancers are hormone receptor positive.

"This suggests that aspirin does not protect against breast cancer in the same way that it protects against other cancers," study researcher Alfred I. Neugut, MD, PhD, tells WebMD.

Older Women Benefit Most

Millions of people take a daily aspirin either to lower their risk of heart disease or treat pain, and studies have also linked daily aspirin use to a reduced risk of colorectal cancer. While aspirin/NSAID treatment has been linked to reductions in breast cancer risk ranging from 20% to 40%, no previous study has examined whether its protective effects are limited to specific breast cancer types.

In an attempt to do this, Neugut and colleagues from New York's Columbia University interviewed more than 1,400 women with breast cancer and 1,420 women without the disease over the course of a year. The researchers asked the women questions about their use of aspirin and other pain relievers, however they did not specifically ask about the dose of their medication.

They found that taking aspirin at least once a week for six months or longer reduced the risk of breast cancer by 20%, compared with women who never took aspirin. Taking a daily aspirin reduced risk by more than 25%.

Although aspirin's protective benefits were seen in women of all ages, the greatest effect was in postmenopausal women.

The protective effect of aspirin was not as strong as that of hormone blockers such as tamoxifen (which help prevent breast cancer by blocking the effects of estrogen), Neugut says.

The study shows that the benefits of aspirin are probably limited to postmenopausal women who may already be taking aspirin to help prevent heart disease or treat pain.

"Since the bulk of breast cancers in younger women are not hormone receptor positive, this is not a prevention strategy that is likely to be recommended for women under 50," he says.

More Study Needed

The findings help clarify the role of aspirin and other anti-inflammatory drugs in the prevention of breast cancer. But other studies are needed to determine the optimal dosage and best treatment strategy, Vanderbilt University researcher Raymond DuBois, MD, PhD, tells WebMD.

DuBois, who is also studying NSAIDs for cancer prevention, says the benefits of the treatment must be weighed against the potential risks. Regular aspirin use has been linked to an increased risk of ulcers and stomach bleeding.

"Right now all we can say is that women who are taking aspirin to lower their cardiovascular risk may also derive an additional benefit in terms of breast cancer risk," he says.