A survey of unproven cancer remedies and their users in an outpatient clinic for cancer therapy in Finland

Herbal remedies in the United States: potential adverse interactions with anticancer agents

PURPOSE

Interest in the use of herbal products has grown dramatically in the Western world. Recent estimates suggest an overall prevalence for herbal preparation use of 13% to 63% among cancer patients. With the narrow therapeutic range associated with most anticancer drugs, there is an increasing need for understanding possible adverse drug interactions in medical oncology.

METHODS

In this article, a literature overview is provided of known or suspected interactions of the 15 best-selling herbs in the United States with conventional allopathic therapies for cancer.

RESULTS

Herbs with the potential to significantly modulate the activity of drug-metabolizing enzymes (notably cytochrome p450 isozymes) and/or the drug transporter P-glycoprotein include garlic (Allium sativum), ginkgo (Ginkgo biloba), echinacea (Echinacea purpurea), ginseng (Panax ginseng), St John' s wort (Hypericum perforatum), and kava (Piper methysticum). All of these products participate in potential pharmacokinetic interactions with anticancer drugs.

CONCLUSION

It is suggested that health care professionals and consumers should be aware of the potential for adverse interactions with these herbs, question their patients on their use of them, especially among patients whose disease is not responding to treatments as expected, and urge patients to avoid herbs that could confound their cancer care.

pS2 expression induced by American ginseng in MCF-7 breast cancer cells

BACKGROUND

Alternative medicines are frequently used by patients with breast cancer for general health benefits. American ginseng, an herbal remedy, purportedly alleviates treatment-induced postmenopausal symptoms.

METHODS

Estrogenic potential of American ginseng root extract to induce the expression of pS2, an estrogen-regulated gene, was evaluated in breast cancer cell lines MCF-7, T-47D, and BT-20 by Northern and Western blot analysis. Competitive studies were performed with ginseng in combination with tamoxifen. Cell proliferation assays were performed using the tetrazolium dye procedure and direct cell count.

RESULTS

Ginseng and estradiol induce the expression of pS2 RNA and protein in MCF-7 cells, whereas tamoxifen suppresses expression. Neither ginseng nor estradiol induced increased pS2 expression in T-47D or BT-20 cell lines. Although estradiol exhibited a proliferative effect and tamoxifen had an inhibitory effect, ginseng demonstrated no significant effect on cell proliferation.

CONCLUSIONS

The results of this study suggest that ginseng may exhibit estrogenlike effects on estrogen receptor-positive breast cancer cells by inducing pS2 expression and that the effect of ginseng may be mediated in part through the estrogen receptor. Because ginseng does not exhibit a proliferative effect, it may play a protective role against breast cancer rather than serve as a mitogen.