Study: Black Cohosh May Increase Breast Cancer Risk

Black cohosh, an herbal therapy widely used to ease the hot flashes of menopause, may increase a woman's risk of developing breast cancer or promote spread of the disease to other parts of the body, according to Duquesne University researchers.

"Although it is unfortunate to be eliminating another option for women needing therapies to relieve menopausal symptoms, our findings suggest that women who may be at high risk of having an undetected breast tumor and certainly those who do have breast cancer should proceed with great caution – or simply avoid – taking black cohosh," said lead researcher Vicki Davis.

The results, presented at the annual meeting of the American Association for Cancer Research, are another setback for women looking for a way to ease the symptoms of menopause. Several earlier studies have found that hormone replacement therapy increases the risk of heart disease.

Another widely used alternative therapy, red clover, was found ineffective in easing menopause symptoms in a study reported this week in the Journal of the American Medical Association.

In the black cohosh study, researchers fed the herb to female mice bred so that they were prone to breast cancer in a dosage comparable to the amount of the supplement normally recommended for menopausal symptoms.

While the incidence of new breast cancer was not higher, mice taking black cohosh that did develop breast cancer saw it spread to the lungs 27.1 percent of the time compared to 10.9 percent in mice not taking the supplement.

"The increase in lung tumors suggests that this herbal therapy may increase the aggressiveness of the mammary cancer," the researchers reported. "The data suggests that black cohosh at normal doses recommended for women with menopausal symptoms may promote progression to metastatic disease in women with early stage breast cancer."

Other Sources: American Association for Cancer Research