Given the increasing use of alternative menopause treatments, we evaluated the effect of several herbal preparations used for menopause relief on the proliferation of estrogen-sensitive breast cancer cells (MCF-7) as a means of assessing appropriateness for use in women at risk for estrogen-sensitive breast cancer.
An MCF-7 cell culture model, as described previously, 1 was used to evaluate the estrogen-agonist and -antagonist activity of commercially available herbal menopause preparations containing red clover, soy, black cohosh, or a combination of herbs. Each test substance was evaluated for cytotoxic effects before conducting the proliferation assays.
Commercially available products containing soy, red clover, and herbal combinations induced an increase in the MCF-7 proliferation rates, indicating an estrogen-agonistic activity in the absence of estradiol. In contrast, an isopropanolic black cohosh extract (Remifemin Menopause) did not stimulate MCF-7 growth and exerted inhibitory effects on cellular proliferation. None of the tested products enhanced estradiol-induced cell proliferation. The black cohosh preparation and one of the herbal combinations exhibited strong estrogen-antagonistic effects.
The lack of proliferative effects of isopropanolic black cohosh extract on estrogen-sensitive breast cancer cells in vitro suggests a favorable safety profile for use in women with a history of breast cancer. Alternatively, preparations containing red clover, soy, and combinations of various herbal ingredients may induce cell proliferation, suggesting that such herbal preparations should be used with caution in the treatment of menopause symptoms in women at risk for, or with a history of, estrogen-sensitive breast cancer.