Women often use natural therapies because they think they are "natural" and therefore safe. This is not always the case as illustrated by the recognised interactions between certain prescribed medications and St John's Wort and case reports of liver toxicity associated with the use of black cohosh. Long-term safety of natural preparations is unknown. It is important that women tell both their doctor and natural therapist all of their medications.

When used properly, natural medicines and therapies generally do not cause side effects. However, not all natural medicines are free from potential harmful effects, and it is important to seek the advice of a trained natural therapist. Another excellent reason for seeking professional advice is to ensure that remedies are not taken indefinitely, but rather prescribed for the duration of time necessary to address the symptoms. For example, a remedy for hot flushes should only be taken for as long as a woman experiences hot flushes. It is not advisable to purchase over the counter natural therapies, as a trained health practitioner should assess a woman's individual needs and her state of health before any treatment is given. Quality of medicines, especially herbal medicines also varies and is often more reliable from a practitioner.

Herbal Medicines and Breast Cancer

For women with early menopause brought on by treatment for oestrogen receptor positive breast cancer, and for whom in most cases hormone therapy (HT) is not recommended, natural therapies are often considered. Many herbs do not have hormonal activity such as those used for mood changes, sleep and tonics. Black cohosh and phytoestrogens which are often considered to have "hormonal activity" will be discussed in detail:

Black Cohosh

In vitro studies using human breast cancer tissue and cell lines have demonstrated non- stimulatory or oestrogen-antagonist effects of Black cohosh . However, an animal study of female mice with breast tumours demonstrated an increase in the spread of lung tumours in the group fed black cohosh. No change in the number of breast tumours in the treated group compared to the control group was observed. New evidence suggests that the mechanism for relief of hot flushes may be due to the selective effects of black cohosh on the serotoninergic system and may not be due to oestrogenic properties

There have been two clinical trials on black cohosh and breast cancer patients to date. In an open-label randomised clinical trial over 12 months, black cohosh reduced the number and severity of hot flushes in premenopausal (age 35-52) breast cancer survivors on Tamoxifen treatment). In a second study of only two months duration, black cohosh was no better than placebo for reducing number and intensity of hot flushes, in women with a history of breast cancer. More than two thirds of the women were on Tamoxifen in this study and possibly the short duration of study limited the results.

The most important factor is to get the approval of the oncologist and breast specialist before commencing treatment with black cohosh. Of all the herbal medicines that a breast cancer survivor may consider using, black cohosh has the most research supporting its use and has the greatest amount of safety data. Longer trials of five years or more are needed to establish breast cancer safety data more conclusively. Black cohosh is only indicated for hot flushes, vaginal dryness and aches and pains and very importantly should only be taken for as long as symptoms persist.

Phytoestrogens

There is a great deal of controversy about the use of phytoestrogens in women with breast cancer. Conflicting evidence exists as to the efficacy in relieving menopausal symptoms and the effect of phytoestrogens on the growth of tumours in vitro.

A recent meta-analysis of 18 epidemiologic studies (Trock, BJ. Hilakivi-Clarke, L and Clarke, R. 2006 12 case-control and 6 cohort or nested case-control) published between 1978-2004 showed a small reduction in the risk of breast cancer, with high soy intake versus low intake among all women. Importantly it demonstrated that highly processed soy supplements such as soy protein isolate, isoflavone-rich soy extracts or isoflavone capsules exhibit activity not present in foods made from soy beans or soy flour, and the authors conclusion was that such highly processed soy supplements are not recommended for women at high risk for breast cancer or breast cancer survivors. There is no data to suggest that the consumption of soy foods in amounts consistent with an Asian diet is detrimental to breast health.

Content updated June 25, 2007