Case-Control Study of Phyto-Oestrogens and Breast Cancer.
Case-Control Study of Phyto-Oestrogens and Breast Cancer.
Year: 1997
Authors: D Ingram, K Sanders, M Kolybaba, D Lopez.
Publication Name: Lancet.
Publication Details: Volume 350 (9083); 990.
Abstract:
Phytestrogens are a group of naturally occurring chemicals derived from plants which have a structure similar to estrogen. Several studies in animals and humans have reported that phytoestrogens have potentially anticarcinogenic biological activity. They have been shown to have antiangiogenic, estrogenic and anti-estrogenic properties and can inhibit the activity of enzymes involved in estrogen metabolism. Asian populations who consume large amounts of phytoestrogens from soybean products have a lower frequency of breast and prostate cancer than Western populations where the intakes of phytoestrogens are much lower. This paper reports a case-control study undertaken to assess the association between phytoestrogen intakes (as measured by urinary excretion) and the risk of breast cancer. Women with newly diagnosed early breast cancer were interviewed by means of dietary questionnaires. A 72 hour urine collection and blood sample were taken. Controls were randomly selected after matching for age and area of residence. 144 pairs were included for analysis. Urine samples were assayed for the isoflavonic phytoestrogens daidzein, genistein, and equol, and the lignans enterodiol, enterolactone, and matairesinol. After adjusting for age at menarche, parity, alcohol intake, and total fat intake, the authors reported that a high urinary excretion of both equol and enterolactone was associated with a substantial reduction in breast-cancer risk. For most other phytoestrogens there was a reduction in risk, but it did not reach significance. The investigators concluded that a substantial reduction in breast-cancer risk among women appears to be associated with a high intake of dietary phytoestrogens, in particular the isoflavone equol derived from soybeans and the lignan enterolactone, which is found in high concentrations in flaxseed. The authors note that their findings could be important in dietary recommendations aimed at the prevention of breast cancer.
