Women with breast cancer who use the herbal remedy black cohosh instead of hormones to treat their hot flashes may be unknowingly creating a new health risk for themselves, researchers at the Yale University School of Medicine have found.
Black cohosh, often suggested as a therapy for menopausal symptoms, seemed to increase the toxicity of two common chemotherapy drugs in a new study of laboratory-grown breast cancer cells.
Dr. Sara Rockwell, co-author of the study, told Reuters news service that black cohosh appears to make two forms of chemo more potent: doxyrubicin (Adriamycin) and docetaxel (Taxotere). Studies showed no effect on the potency of another chemo drug, Cisplatin, or on radiation therapy.
"If this were an effect just on the tumor cells, that would be a good thing because it would mean you get more antitumor effect for a person on black cohosh," Rockwell said. "On the other hand, Adriamycin is used in doses that are nearly toxic."
Serious heart injury is one potential side effect of Adriamycin, along with damage to bone marrow, brain tissue and other fast-growing cells. Adding black cohosh could make the treatment lethal, she said.
More research is needed to determine whether the combination of chemo and black cohosh causes the same results in women's bodies as it did in the laboratory.
Some breast cancer mutations are fueled by the hormones estrogen and progesterone. Because of recently publicized links between hormone-replacement therapy and breast cancer, Rockwell noticed a growing number of women diagnosed with cancer were discontinuing their HRT in favor of black cohosh and other supplements.
Rockwell told Reuters that as many as 80 percent of cancer patients take vitamins, minerals or herbs. But combining strong medicine with powerful herbs can have dangerous consequences if not disclosed to a physician.
Natural Foods Merchandiser volume XXIV/number 5/p.