Breast cancer mortality and diet in the United States.

Internationally, breast cancer mortality is correlated with intestinal lactase sufficiency and dairy product consumption beyond childhood. Within the United States, age-adjusted breast cancer mortality is positively associated with consumption of milk, butter, and total milk fat in regional analyses, and it is associated with milk demand in state-based analyses. Breast cancer mortality is also positively associated with demand for total calories, protein, fat, beef, and table fats (butter and margarine), and it is negatively associated with egg demand. Only the associations with milk and egg demand, however, survive when the Southern states are eliminated from the analyses or when either age of first marriage or income is controlled. The associations with milk and egg demand persist despite multiple controls for other dietary and demographic variables, although the association with milk demand loses statistical significance in some second- and third-order partial correlations. The inverse correlation with egg demand is strong but in the opposite direction from what might have been expected from previous studies. The correlation between milk demand and breast cancer mortality, although weaker, is consistent with results from previous studies, and it suggests a possible special role for dairy products in the etiology of breast cancer.