Black cohosh has become a popular alternative therapy for women experiencing the hot flashes, mood swings, and other unpleasant symptoms of menopause. New research finds that the herbal remedy also might be effective for combating breast cancer.Researchers at Columbia University treated breast cancer cells with actein, one of the active components in black cohosh, and looked at its effect on the genes that influence breast cancer cell growth-and death. They identified five genes that were altered by actein treatment, all of which play a role in how cells respond to DNA damage and other stressors that can promote cancer cell growth.
Actein, which belongs to a group of natural plant compounds called triterpene glycosides, appeared to affect breast cancer cells in two stages, according to study author Linda Saxe Einbond, PhD, Associate Research Scientist at the Columbia University College of Physicians and Surgeons. In the first, or survival-response stage, actein could induce the cancer cells to grow. But when actein is given at higher doses and over longer periods of time, it triggers cancer cells to enter the apoptotic stage, which is a form of programmed cell death. Even low levels of actein were able to curb the proliferation of breast cancer cells when combined with chemotherapy drugs, suggesting that actein might enhance the effectiveness of chemotherapy if the two treatments are partnered.
“The effect depends on the dose and duration of treatment with actein, so if you increase the dose or duration, or combine it with chemotherapy agents, it could be much more active,” Dr. Einbond says.
This study isn’t the only evidence that black cohosh might be effective against breast cancer. In research published in the April, 2007 International Journal of Cancer, researchers from the University of Pennsylvania School of Medicine found that women who took a supplement called Remifemin, which is derived from black cohosh, had a 53 percent lower risk of breast cancer than women who didn’t take the supplement. Other research has suggested black cohosh also might help prevent breast cancer from recurring.
However promising the results have been so far, it’s too early to recommend black cohosh for breast cancer prevention or treatment, Dr. Einbond says. For one, researchers haven’t yet ruled out the risk of potentially serious side effects. Particularly of concern is a 2003 study from Duquesne University, which found that in mice with an invasive strain of breast cancer, black cohosh significantly increased the risk of the cancer spreading to the lungs. “This study wasn’t published and it hasn’t been confirmed,” Dr. Einbond says. But, she says, the results warrant further research. For now, the National Institutes of Health advises women with breast cancer to avoid taking black cohosh until doctors understand more about its effects on breast tissue.
Also lacking in evidence is exactly how the body metabolizes black cohosh. It’s unknown whether a single oral dose would provide enough actein to provoke the desired response on breast cancer cells. Researchers are trying to answer some of these questions by studying the effects of actein and other triterpenes from black cohosh in animal models.
Einbond, Linda Saxe, et al. The growth inhibitory effect of actein on human breast cancer cells is associated with activation of stress response pathways. International Journal of Cancer, 2007;121:2073-2083.
Davis V, et al. Effects of black cohosh on mammary tumor development and progression in MMTV-neu transgenic mice. Abstract. Proceedings of the AACR, Vol 44, 2nd ed., July 2003.
National Institutes of Health. “Questions and Answers about Black Cohosh and the Symptoms of Menopause.” http://ods.od.nih.gov/factsheets/BlackCohosh.asp
Rebbeck TR, et al. A retrospective case-control study of the use of hormone-related supplements and association with breast cancer. International Journal of Cancer, April 2007;120(7):1523-1528.