LAUSR

Abstract Endocrine therapy in breast cancer survivors can cause severe ‘climacteric’ symptoms, which may compromise therapy adherence. To determine whether such symptoms can be treated with herbal medication containing black cohosh in the form of isopropanolic Cimicifuga racemosa extract (iCR) alone or in fixed combination with St John’s wort (Hypericum perforatum [HP]) (iCR + HP), a systematic literature search was conducted. Results were viewed in relation to experimental data and metabolism of endocrine therapies. Most breast cancer survivors receiving endocrine therapy experienced reductions in climacteric symptoms under iCR/iCR + HP. Tamoxifen’s interference potential may be countered by using higher iCR doses or iCR + HP. No estrogen-like effects at the breast or on hormones were seen. After breast cancer, even if receiving tamoxifen, patients using iCR/iCR + HP had significantly increased recurrence-free survival rates compared to non-users. These results are substantiated by experimental data demonstrating antiproliferative and anti-invasive effects of iCR in breast cancer cells and enhancement of the antineoplastic effects of tamoxifen. There are no known clinical interactions for iCR and HP with endocrine therapies. The HP extract used in iCR + HP did not exhibit any clinically relevant interaction potential. In conclusion, with its positive benefit–risk profile, iCR/iCR + HP may offer a safe non-hormonal therapeutic option for breast cancer survivors receiving endocrine therapy.