A controlled trial of a soy drink containing phytoestrogens, naturally occurring substances which are thought to help combat the effects of the menopause, has shown that the product was ineffective in combating hot flushes in post-menopausal women who had been treated for breast cancer.
The results of the trial are published in the 15 March issue of the Journal of Clinical Oncology.
Researchers from the Vancouver Cancer Centre, British Columbia, Canada, led by Dr Cheri L. Van Patten, studied 123 post-menopausal breast cancer survivors. The women were randomly assigned 500 mL/day of a soy drink containing 90 mg of isoflavones, or a rice drink as a placebo.
Each of the patients made a record of the number and severity of the hot flushes they suffered each day over a four-week period prior to treatment, and in the 12-week period during which they received the soy drink. The researchers discovered that there was no significant difference in the number of hot flushes, or the severity of them, between the women taking the soy drink and the women receiving the placebo. Both groups noted a reduction in the number of hot flushes, but the researchers put this down to a placebo effect.
Furthermore, Dr Van Patten's team noted that both groups of patients experienced mild gastrointestinal side effects, although the women receiving the soy drink experienced more frequent and more severe side effects.
The researchers concluded that "this randomised, placebo-controlled, double-blind clinical trial does not support the use of a soy beverage containing phytoestrogens as a treatment for hot flushes in breast cancer survivors. These results concur with other studies that also demonstrated a reduction in hot flushes with both soy and placebo but that did not find a statistically significant difference between groups."