evidence suggests that alcohol enhances the expression of estrogen receptors in breast cells (Fan et al. 2000), which would increase breast cancer risk.Both in women with a normal menstrual cycle and in women taking oral contraceptives, blood concentrations of acetaldehyde after alcohol consumption were shown to be particularly high when estradiol levels reached their highest during the menstrual cycle (Eriksson et al. 1996). This could impact cancer risk because under these conditions the two risk factors acetaldehyde and estrogen would be combined.In premenopausal women, alcohol ingestion has been associated with higher estrogen concentrations in the blood, although some studies observed this effect only in women taking oral contraceptives (Singletary and Gapstur 2001).In another study of healthy premenopausal women, the administration of alcohol doses as low as 0.225 g pure alcohol per kg body weight (corresponding to approximately one drink) resulting in blood alcohol concentration not exceeding 25 mg per 100 mL (0.025 percent), caused an increase in serum estradiol concentrations of 27 to 38 percent while alcohol was detectable in the blood (Coutelle et al. 2004). This effect was observed during all phases of the menstrual cycle.For postmenopausal women, an increase of estrogens following alcohol consumption appears to depend on
