A proprietary extract of black cohosh (Actea racemosa) sold in the US and Europe as Remifemin has long been purported as an alternative to hormone replacement therapy in menopause and perimenopause. Several trials have questioned the efficacy of this herb (one discussed on this blog) and the NIH has been concerned about sporadic reports of liver toxicity associated with some preparations of the herb. In the literature, black cohosh has been described in various instances as a phytoestrogen, an antiestrogen, an estrogen-receptor modulator, or devoid of any estrogenic activity. So, even I am confused by a recent press release on two articles showing 1) lack of promotion of breast cancer risk factors and, more provocatively, 2) association with decreased breast cancer risk:
Many women are choosing dietary supplements for the management of menopausal symptoms — especially since serious health concerns have been raised about hormone replacement therapy (HRT). Remifemin(R) black cohosh extract, the most extensively researched, non-prescription menopausal therapy has been found to safely and effectively reduce hot flashes, night sweats and irritability. Now, a study published in the International Journal of Cancer: 120, 1523-1528 (2007), has shown that this proprietary herbal product lowers the risk of breast cancer by as much as 60%.
“The standardized Remifemin(R) black cohosh extract has antiestrogenic, antiproliferative and antioxidant properties,” said Dr. Eckehard Liske, Director of the International Medical Department, Schaper & Bruemmer GmbH & Co KG, Salzgitter, Germany. “Rebbeck’s research suggests that Remifemin(R) may help in reducing the risk of breast cancer.”
Something just doesn’t seem right about this work as a recent paper noted that a concentration of 77 micrograms/mL black cohosh extract was required to block breast cancer cell invasiveness by 51% in cell culture. Given that the recommended daily dose of this extract is 20 mg, there is no way that such concentrations could be achieved in patients. The press release also conveniently avoids recent trials showing no benefit of Remifemin brand of black cohosh extracts over placebo in alleviating the vasomotor symptoms of menopause.
But to claim that this extract can prevent primary risk or risk of recurrence of breast cancer seems like an even greater reach, although I am aware that similar findings were indeed published in a peer-reviewed journal (International Journal of Clinical Pharmacology and Therapeutics). In this other paper, breast cancer recurrence was reduced by 17%, not the 60% claimed in the new International Journal of Cancer paper (the abstractnotes an odds ratio of 0.39 for black cohosh but 0.47 for black cohosh or Remifemin, hence my confusion). I’ll have to consult with some of my clinical colleagues to look at the methodology used in both of these papers. The latter, however, comes from the University of Pennsylvania and was supported by an NCI program project grant.
But for now, these claims for black cohosh seem to be more of a public relations campaign intended to capitalize on fears surrounding hormone replacement therapy. I welcome comments on this article if you have access to this full report or the newest paper in the International Journal of Cancer.