Cancer patients and survivors often self-administer complementary and alternative medicine (CAM) to augment conventional treatments, improve health, or prevent recurrence. Herbal tonics like Essiac® and Flor-Essence® are popularly used by breast cancer patients and survivors because of anecdotal evidence that the tonics can treat or prevent disease. We are using cellular and animal models to evaluate the consequences of Flor-Essence® and Essiac® exposure on the breast. Cell proliferation assays in estrogen receptor positive (MCF-7) and estrogen receptor negative (MDA-MB-436) breast cancer cells demonstrated that exposures ranging from 1 to 8% Essiac® and Flor-Essence® stimulate growth up to 180% compared to untreated cells. In estrogen receptor activation assays, Essiac® and Flor-Essence® stimulate estrogen receptors to levels similar to physiological estrogen. In Sprague Dawley rats, both Flor-Essence® and Essiac® seem to promote palpable tumor formation of PhIP-induced mammary tumors. COMET assays of MCF-7 cells suggest that Flor-Essence® and Essiac® are not having an effect of PhIP-induced DNA damage. These studies are important for the development of science-based recommendations for CAM use among women in our communities. (This work was performed under the auspices of the U. S. DOE by the University of California, LLNL under Contract No. W-7405-Eng-48 and supported by CBCRP #9WB-0173 and NCCAM # R21 AT 001730)

[Proc Amer Assoc Cancer Res, Volume 46, 2005]