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Breast Cancer Warnings For Black Cohosh
May Increase Spread of Cancer

black cohosh"Chemopause" is the name used for the sudden onset of menopausal symptoms that accompany many forms of chemo.

Turning to herbal remedies seemed safe for breast cancer patients. Hormone replacement was definitely not a good idea, but herbs are "natural".

Black cohosh is high on the list of herbs that survivors have found bring relief from hot flashes and other uncomfortable physical effects of estrogen deprival that breast cancer drugs create.

Research is finding that the dietary supplement herbal extract, black cohosh, may not be a safe alternative therapy for breast cancer.

It may be especially dangerous for those who have undetected breast tumors or who are going through chemotherapy treatments.

A study funded by the Susan G. Komen Foundation was presented at the 94th annual meeting of the American Association for Cancer Research.

Researchers used a transgenic mouse model in which the female mice spontaneously develop mammary tumors through the activation of an oncogene common in human breast cancer.

These mammary tumors spread in time to other parts of the body, as occurs with invasive breast cancer.

To determine the effect of black cohosh on these processes, mice were fed the herbal extract in a dosage comparable to women ingesting 40 mg/day (the amount of a standardized herbal supplement normally recommended for menopausal symptoms). The sexually mature female mice were fed the black cohosh diet for 12 months.

In black cohosh-treated female mice, the incidence of new tumors was not increased, suggesting that black cohosh will not increase or decrease a womens risk of developing breast cancer.

However, in the mice that developed mammary tumors, there was an increase in the number of tumors that spread to the lung (27.1% of treated mice compared to 10.9% of the mice on the control diet).

The increase in the number of lung tumors per female after long-term exposure to black cohosh suggests that this herbal therapy may increase the aggressiveness of the mammary cancer.

The data presented suggest that black cohosh (at normal doses recommended for women with menopausal symptoms) may promote progression to metastatic disease in women with early stage breast cancer.

"Although it is unfortunate to be eliminating another option for women needing therapies to relieve menopausal symptoms, our findings suggest that women who may be at high risk of having an undetected breast tumor and certainly those who do have breast cancer should proceed with great caution or simply avoid taking black cohosh until we learn if there are ways to circumvent these adverse effects, said Vicki Davis, Ph.D., lead researcher and assistant professor, Mylan School of Pharmacy and Graduate School of Pharmaceutical Sciences at Duquesne University.

This announcement together with a study by Dr. Sara Rockwell of Yale University School of Medicine in New Haven, Connecticut reported at the ASCO conference in April, 2003 makes the safety of black cohosh use in breast cancer patients questionable.

The ASCO study found that black cohosh increased toxicity of the breast cancer chemotherapy drugs doxorubicin (Adriamycin) and docetaxel (Taxotere), but not a third, cisplatin.

These studies reinforce the fact that herbs can be potent medicines. Just because something is "natural" does not make it safe. A drug, whether it comes from an herb or a laboratory, has side effects that must be taken into account before use.

Studies on herbal therapies that women already use is a good sign. Hopefully it will increase the knowledge base of doctors who treat breast cancer patients. It should reinforce the need to let the doctor know if you are taking any drugs besides the cancer treatments that have been prescribed. Drug interactions are possible with herbs and other natural remedies - or over the counter medications - and your cancer meds.

Source:94th AACR Annual Meeting & ASCO

Elsewhere on the Web:

Questions and Answers About Black Cohosh and the Symptoms of Menopause

Dangers of Black Cohosh As HRT

Black cohosh (Cimicifuga racemosa [L.] Nutt.) - Mayo

July 12, 2003

Last updated July 8, 2009




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