A dietary pattern derived to correlate with estrogens and risk of postmenopausal breast cancer.

Circulating estrogens are an established risk factor for breast cancer and some data suggest that diet may influence estrogen levels. Therefore, using a subsample (n = 550) of women from a large cohort, we applied reduced rank regression to identify a dietary pattern that was correlated with estradiol and estrone sulfate. We then adapted the pattern to be used with the full cohort (n = 67,802) and prospectively assessed its association with postmenopausal breast cancer. The estrogen food pattern, characterized by higher intakes of red meat, legumes, and pizza, but lower intakes of coffee and whole grains, was modestly but significantly correlated with estradiol (r = 0.14) and estrone sulfate (r = 0.20). During 22 years of follow-up, we ascertained 4,596 incident breast cancer, with 2,938 estrogen receptor-positive tumors and 689 estrogen receptor-negative tumors. However, after adjusting for potential confounders, we did not observe any association with overall estrogen receptor-positive or estrogen receptor-negative breast cancer. In conclusion, diet pattern appeared to only have modest association with estrogens, and was not associated with postmenopausal breast cancer risk. Although these results were null, it should be repeated in other populations as differences in food intake may yield a dietary pattern with stronger association with estrogens.