Dietary patterns and breast cancer: a review with focus on methodological issues.

Available information on dietary patterns (multiple dietary components operationalized as a single exposure) and cancer is still sparse. This review presents papers published to date that have identified dietary patterns according to all the existing approaches and have assessed their association with breast cancer. Nineteen articles published since 1995 were identified based on studies conducted in various populations across many countries. The majority of them identified a posteriori dietary patterns, mainly using principal component factor analysis. Six studies did not find associations between any of the identified dietary patterns and breast cancer. Nine studies identified one dietary pattern significantly associated with breast cancer, and the remaining four identified two to four dietary patterns related to breast cancer. Although the body of literature has recently increased, a meaningful assessment of the association between dietary patterns and breast cancer still calls for extra effort to refine the statistical techniques and to address the issue of reproducibility of dietary patterns.