Data from this study showed women who took hormone replacement therapy had lower rates of heart disease -- a finding that was not confirmed in a randomized study. Similarly, it showed that women who took vitamin E had lower rates of heart disease. Later research found this not to be true; vitamin E might even be harmful in large doses.
"The vitamin E story needs to humble us here," said Dr. Tim Byers, deputy director of the University of Colorado Cancer Center in Denver. "This is especially important as so many breast cancer survivors will be jumping at this... This will inevitably be a news story. Covering it with the right amount of uncertainty will be important."
Others agree that it could be dangerous if women started taking aspirin because of these findings. "Because frequent aspirin use can have serious side effects such as (occasionally fatal) gastrointestinal bleeding, it's not something I would want to encourage based on this study alone," said Sander Greenland, an epidemiologist at UCLA.
But while it may be too soon to take aspirin for breast cancer, there could be other reasons to take it.
"There are many women with heart disease for whom aspirin is recommended," said Besser. "It is worth speaking with your doctor to find out if you fall into that group."