WOMEN'S HEALTH Study: Aspirin cuts breast cancer risk

The drug appeared to inhibit tumors that respond to certain hormones.
SCRIPPS HOWARD
Women who regularly use aspirin appear to have a reduced risk of certain types of breast cancer, according to new research.
Those who took at least one aspirin a week for six months or longer had a 20 percent lower risk of breast cancer than women who did not use aspirin, the study found.
Women who took at least seven aspirin tablets weekly for six months or longer reduced the risk by 28 percent.
"Our data bolster the case for the use of aspirin and other nonsteroidal anti-inflammatory drugs as preventive agents against breast cancer, particularly among post-menopausal women," said Mary Beth Terry, a researcher at Columbia University in New York City and lead author of the report published today in The Journal of the American Medical Association.
Other research has found that aspirin helps reduce deaths from heart disease and colon cancer, and perhaps other types of cancer, but earlier small studies that tried to measure aspirin's effect on breast cancer gave mixed results.
How it works
Terry said the protective mechanism in breast cancer is probably different from what aspirin does to inhibit intestinal cancers.
The fact that aspirin seemed to inhibit breast tumors that react to the sex hormones estrogen and progesterone but not to tumors that don't react to the hormones was particularly significant. It suggests that the drug somehow interferes with the chain of hormone production. Scientists know that along with reducing inflammation, aspirin blocks production of a precursor to estrogen.
About 70 percent of women who develop breast cancer have the form of tumor that reacts to the positive hormone receptor.
The researchers analyzed data on 1,442 breast cancer patients age 59 on average and a comparison group of 1,420 healthy women without the disease. All were asked about their use of three pain relievers: aspirin, ibuprofen and acetaminophen.
Fewer women in the study used ibuprofen -- sold under brand names such as Advil and Motrin -- and the results were inconclusive. No reduced risk was found among users of acetaminophen, the active ingredient in Tylenol.
The effect was greater in women who had gone through menopause than in younger women, which the researchers said would be expected because hormone-sensitive tumors are more common in older women.
Dr. Paul Tartter, a breast cancer surgeon at St. Luke's-Roosevelt Comprehensive Breast Cancer Center in New York City who was not involved in the study, said "their theory on this biologically makes sense. We know all the risk factors for this type of tumor reflect the number of normal menstrual cycles that a woman has. This is the first realistic intervention that might reduce serum estrogen levels."
Dr. Raymond DuBois, director of cancer prevention at Vanderbilt University's Vanderbilt-Ingram Cancer Center, said the study and other recent research lay strong groundwork for the biological effects of aspirin on breast cancer. But he cautioned in an editorial that "current information is insufficient to make any definite recommendations to patients" about how much or how often to take aspirin, which can have dangerous side effects, such as stomach bleeding and ulcers.
Tartter said more research is needed to understand how aspirin works and should be dosed.