A prospective study of major dietary patterns and the risk of breast cancer.

Our aim was to study the broader eating patterns that potentially reflect many dietary exposures working together in their association with breast cancer risk. Using data from a prospective study of 61,463 women with an average follow-up of 9.6 years and 1,328 incident cases of breast cancer, we conducted a factor analysis to identify major dietary patterns. Proportional hazards regression was used to estimate hazard ratios. We found no association between the "Western" dietary pattern (characterized by such foods as red and processed meats, refined grains, fat, and sweets) or the "healthy" dietary pattern (fruit and vegetables, fish and poultry, low-fat dairy, and whole grains) and breast cancer risk. However, women who were in the highest category of the "drinker" dietary pattern (wine, beer, and spirits) had a moderately increased risk (rate ratio = 1.27; 95% confidence interval, 1.06-1.52; P for trend, 0.002). The positive association was somewhat weaker among women below 50 years of age, a finding not inconsistent with chance. Our results are in agreement with the majority of previous studies that show alcohol consumption moderately increases the risk of breast cancer, but our results do not support any association between breast cancer risk and the "Western" or "healthy" dietary patterns.