Nutrition and breast cancer

The high rates of breast cancer in Western countries have suggested that some features of a Western diet may increase breast cancer risk. Most of the established risk factors for breast cancer are hormonal, and nutrition may affect breast cancer risk through changes in hormone metabolism. The only well established diet-related risk factor for breast cancer is obesity, which increases breast cancer risk in postmenopausal women by around 50%, probably by increasing serum concentrations of free oestradiol. Moderate alcohol intakes increase breast cancer risk by about 10-20%, perhaps also by increasing oestrogen levels. Dietary fat has not been shown to alter circulating hormone levels or breast cancer risk. Phyto-oestrogens can affect hormone metabolism, but data on phyto-oestrogens and breast cancer risk are inconsistent. An emerging hypothesis is that nutrition may affect breast cancer risk by altering levels of growth factors such as insulin-like growth factor-1. © 2001 Harcourt Publishers Ltd