Jacobson, J.S., Troxel, A.B., Evans, J., Klaus, L., Vahdat, L., Kinne, D., … Grann, V.R. (2001). Randomized trial of black cohosh for the treatment of hot flashes among women with a history of breast cancer. Journal of Clinical Oncology, 19, 2739–2745. 

 To assess the effect of black cohosh on the frequency and intensity of hot flashes in survivors of breast cancer

The study explored the use of black cohosh for treatment of hot flashes among women with a history of breast cancer. The black cohosh and placebo were supplied by the manufacturer. Each participant received 130 tablets and took one tablet twice daily with meals for 60 days.

• Eighty-five participants were enrolled  (59 on tamoxifen, 26 not on tamoxifen); 42 participants were assigned to treatment; 43 were assigned to placebo; 69 completed all three hot flash diaries.
• Inclusion criteria: Participants had to have completed primary therapy, including chemotherapy and radiation therapy, at least two months before entering the trial.
• Exclusion criteria: Patients could not be using hormonal replacement therapy for hot flashes, be pregnant, have major psychiatric illness, or have recurrent or metastatic breast cancer.
• Participants were stratified based on if they used tamoxifen.

The study was a randomized clinical trial: two-arm randomization, double-blind, placebo-controlled.

Participants were asked to record in a diary the number of hot flashes and the intensity of each. Participants scored severity as 1 = mild, 2 = moderate, and 3 = severe, for three days before starting to take any study pills, then again on days 27 to 30, and on days 57 to 60. FSH and LH levels were measured in a subset of participants at the first and final visits.

Sample size was chosen for 90% power to detect a 30% difference between groups in mean numbers of hot flashes, with a SD of 4.0. All analyses were stratified by tamoxifen use. The primary efficacy end point was mean numbers of hot flashes at 57 to 60 days. The safety end points were changes in mean levels of FSH and LH at the start and end of study participation associated with treatment. In hot flash intensity, both groups experienced a decline during the first month of study participation. The differences between groups in intensity at the end of the study were not significant. For the overall hot flash activity score, the differences between the treatment and placebo groups adjusted for tamoxifen were not statistically significant. Changes in FSH and LH levels of also did not differ between the two groups.

Data provide little evidence of either harm or benefit from using black cohosh to control hot flashes.

A limitation of this study is that participation lasted only two months.