Alcohol consumption, obesity, estrogen treatment and breast cancer.

Alcohol consumption increases breast cancer risk in postmenopausal women in a dose-dependent manner. The objective of the present study was to determine if the effect of alcohol on mammary cancer is modified by body weight and exogenous estrogen. Ovariectomized mice of various body weights, receiving estrogen or placebo supplementation, and consuming water or alcohol were injected with mammary cancer cells. Alcohol intake resulted in insulin sensitivity and increased tumor growth in obese mice. Exogenous estrogen alone inhibited tumor growth. The combination of estrogen and alcohol overcame the inhibitory effects of estrogen on tumor growth in obese mice. Alcohol consumption increased the circulating estrogen and leptin levels. In conclusion, alcohol and estrogen treatment can modify mammary tumor growth, possibly through the regulation of estrogen and leptin, especially in obese mice.