Do Antidepressants Increase Breast Cancer Risk?
"Epidemiology is really a rather crude tool, and it's effective for identifying increases in risk when the magnitude of the risk is quite high," Kelly says. But that is not the case with antidepressants and breast cancer. Kelly was not involved in the Canadian study, but she has studied links between drugs such as SSRIs, tricyclic antidepressants, and antihistamines and cancer.
Several physicians who spoke to WebMD raised the question of whether depression alone could have been responsible for the increased risk Krieger and colleagues found.
"There's a general theory that depression may make people susceptible to cancers in general, because it can decrease immune function. There has not been any strong data to support that. On the other hand, it hasn't been looked at in a well-designed study," says Bruce Trock, PhD, associate professor of medicine and oncology at Georgetown University School of Medicine in Washington.
Krieger's findings raise other several questions, Trock says, such as: How does the number of women who took antidepressants and didn't get cancer compare to the general population? Were the researchers able to eliminate the impact of known breast-cancer risk factors?
For these reasons, more studies need to be done. At this point, Kelly says, "Women should not avoid taking antidepressants because they're afraid of developing breast cancer. The evidence is not strong enough to justify that type of action."
Says Charles Loprinzi, MD, an oncologist at the Mayo Clinic in Rochester, Minn., who has studied the use of Prozac to relieve hot flashes in breast cancer survivors: "The bottom line must be that you can't put much credence in [these findings]. The numbers are small and consistent with what might have occurred by chance. This is the same sort of risk that people have talked about with alcohol use. It's very, very small indeed."