Recent research suggests that drinking a single alcoholic beverage daily may increase a woman's risk of developing invasive breast cancer by 9 percent. Drinking just over two drinks daily may increase their breast cancer risk by 32 percent. Moderate alcohol consumption increases the risk of breast cancer. Beer, liquor, and white wine all conferred increased risk, but not red wine. It is possible that chemicals in red wine such as resveratrol and other polyphenols could counteract the harmful effects of alcohol. But, the findings don't prove that red wine is safe. Researchers from the Harvard Medical School in Boston, USA, followed 39,876 women. During the 10-year follow up period, 1,190 developed invasive breast cancer and 294 were diagnosed with early-stage disease. Women who consumed 10 grams of alcohol a day - between three-quarters of a drink and one drink - were at 7 percent greater risk of developing breast cancer, and at 9 percent greater risk of developing more advanced disease. Among those who drank 30 grams of alcohol daily, overall risk of breast cancer rose 32 percent, and 43 percent for invasive disease. The increased risk was most substantial for women who had tumours carrying both oestrogen and progesterone receptors, who represented about two-thirds of all breast cancer cases (most breast cancer tumours contain receptors for both oestrogen and progesterone, while some have receptors for just one of the hormones or for neither). Alcohol is thought to affect breast cancer risk by influencing oestrogen levels, and the finding that the link was strongest among women with oestrogen and progesterone receptor positive tumours backs up this hypothesis. Women who were taking postmenopausal hormones also showed a greater risk; those who drank 10 grams of alcohol daily and were on hormone therapy were 84 percent more likely to develop breast cancer than those who didn't drink and weren't taking hormones.
American Journal of Epidemiology,
March 2007