Dietary Patterns and Breast Cancer Risk in Women from Northern Mexico.

We evaluated the association between dietary patterns and breast cancer (BC) subtypes among women from Northern Mexico. From a study of incident cases and population controls that was carried out from 2007 to 2011, a subsample of 509 cases matched 1:1 by age with 509 controls was selected. Information about expression of estrogen receptor (ER), progesterone receptor (PR), and human epidermal growth factor 2 (HER2) was available from medical records to classify BC on luminal (ER + and/or PR+/HER2-), HER2+ (ER+/- and/or PR+/-/HER2+), or triple negative (ER- and PR-/HER2-). Dietary information was gathered using a semiquantitative food frequency questionnaire and a factor analysis was used to obtain dietary patterns. The association between each dietary pattern and BC molecular subtypes was assessed through conditional logistic regression models. Two dietary patterns were identified. The first (mainly characterized by meat, high fat, and sugary cereals) was positively associated with BC (odds ratio, OR = 12.62; 95% CI: 7.42, 21.45); the second (consisting of corn, legumes, and other vegetables) was inversely associated with BC (OR = 0.50; 95% CI: 0.40, 0.62). Both associations remained significant by BC molecular subtypes. These findings could contribute to the development of public health strategies for BC prevention.