Aspirin seen cutting risk of type of breast cancer

Wed Apr 30, 2008 4:00pm EDT  By Will Dunham

WASHINGTON (Reuters) - A daily aspirin may give women modest protection against the most common type of breast cancer, U.S. government researchers said on Wednesday.

The finding reinforced earlier research indicating regular use of aspirin might reduce the risk of so-called estrogen receptor-positive breast cancer, which makes up about three quarters of breast cancer cases.

Researchers led by Gretchen Gierach of the National Cancer Institute, part of the National Institutes of Health, found that women who took aspirin daily cut their risk of developing this type of breast cancer by 16 percent.

"If aspirin is truly risk-reducing, it would be a very exciting finding," Gierach said in a telephone interview.

Estrogen receptor or ER-positive breast cancer is fueled by estrogen and aspirin may interfere with this hormone's activity.

"Even though it's a small reduction in relative risk, since ER-positive breast cancers are the more common types, if this result is confirmed to be true it could have potentially a big public health impact," Gierach said.

The research involved about 127,000 women aged 51 to 72 from around the United States who were cancer-free when the study began. About 18 percent of the women were daily aspirin users. They were tracked for seven years and about 4,500 of them developed breast cancer.

The study did not find any relationship between aspirin and the less-common estrogen receptor-negative breast cancer. It also did not find any protective effect in women who took aspirin less than daily. 

The study, published in BioMed Central's open-access journal Breast Cancer Research, is the latest to suggest aspirin offers benefits beyond relieving headaches and body aches and reducing fevers.

Aspirin is a common anti-inflammatory painkiller that can be used to relieve symptoms of arthritis and prevent second heart attacks and other ailments. Previous research has indicated it also may protect against colorectal cancer.

Gierach said a number of previous studies have looked at the question of aspirin and breast cancer, yielding inconsistent results. Some of the earlier work looked only at aspirin's effect on overall breast cancer without breaking it down by types of the disease, she said.

A study by Columbia University researchers in the Journal of the American Medical Association in 2004 found that women who took aspirin regularly had a modestly lower risk for estrogen receptor-positive breast cancer.

"Our findings are consistent with their findings for aspirin," Gierach said of the Columbia study.

She noted that aspirin can cause serious side effects in some people including ulcers and bleeding.

"A woman would really need to talk to her doctor before starting any new regimen, and weigh the pros and cons of starting a new treatment," said Gierach, whose study is available at