Black cohosh linked to lung metastases in mice

Black cohosh, a herb taken by women to ease menopausal hot flashes, has been linked to cancer, in a North American trial recently published in the journal Cancer Research.

In this study, the effects of black cohosh on mammary tumorigenesis were investigated in the MMTV-neu mouse model due to its similarities to HER2+ breast cancer, including stochastic development of mammary tumors, which frequently progress to metastatic disease. The herb caused a 25% significant increase in the incidence of lung metastases in tumor-bearing animals compared with mice fed the isoflavone-free control diet.

Using an adjusted dose for the mice to correlate to the recommended dose in women (40mg/d), no differences were detected in the incidence or onset of mammary tumors in black cohosh-treated versus control females. The lack of effect on mammary tumor development suggests that black cohosh would not influence breast cancer risk if given to women before tumor formation, the authors noted.