"In this work, we confirm reports by others that aspirin reduces the risk of breast cancer by about 20 percent in some women," said Dr. Marilie D. Gammon, professor of epidemiology at the University of North Carolina at Chapel Hill. "The risk reduction is most pronounced among daily aspirin users -- 27 percent."
Chief among new findings is that the reduction appears to be restricted to women with what are called ER-positive tumors, said Gammon, who works at the UNC School of Public Health. The discovery is biologically plausible because aspirin is thought to work through a chemical pathway in the body called Cox-2, and estrogen appears to interact with that pathway.
"ER-positive breast cancer is the predominant type of breast cancer among postmenopausal women, and postmenopausal women make up about 75 percent of all newly diagnosed breast cancer cases in the United States," she said. "In contrast, ER-positive breast cancer is not prevalent among postmenopausal women in Japan, for example, where breast cancer rates are much lower than they are in the U.S.
"If we can reduce the risk of ER-positive breast cancer through such efforts as taking an aspirin-like chemopreventive, we could potentially reduce the incidence breast cancer among American women," Gammon said. "This would be a big deal."
A report on the research appears as the lead article in the May 26 issue of the Journal of the American Medical Association.
Besides Gammon, authors include Drs. Mary Beth Terry, assistant professor of epidemiology, and Alfred I. Neugut, professor of epidemiology, both at Columbia.
Gammon is principal investigator of the Long Island Breast Cancer Study Project, one of the most comprehensive environmental epidemiologic studies ever done on that cancer. First
Contact: David Williamson
University of North Carolina at Chapel Hill