Dietary Patterns and Risk of Breast Cancer among Pre and Post-Menopausal Women: A Case-Control Study in Iran

Background: Most of previous studies have investigated the association of specific food or nutrient with risk of breast cancer (BC) rather than overall diet and there is lack of evidence regarding dietary pattern in BC development. This study aims to examine the association between dietary patterns and risk of BC among Iranian women. Methods: This case–control study was carried out on 453 BC women and 496 healthy controls. A reliable and valid FFQ was used to evaluate usual dietary intake. Factor analysis was also applied to address the most major dietary patterns which were known as the healthy and unhealthy dietary patterns. Results: Those in the highest quartile of healthy dietary pattern had lower risk of BC (P = 0.001). However, being in the highest quartile of unhealthy pattern was associated with 2.04-fold increase of BC risk (P = 0.004) compared to the lowest quartile. In premenopausal women, risk of BC in upper quartile of healthy pattern was lower than the lowest quartile (OR = 0.47; CI = 0.26 – 0.83, P = 0.004). More adherence to the unhealthy dietary pattern was associated with higher risk of BC (OR = 2.85; 95% CI = 1.57- 5.17, P < 0.0001).  No significant association was observed between the healthy or unhealthy dietary patterns among postmenopausal women. Conclusion: The findings indicated that the healthy dietary pattern could be considered as a protective factor in terms of BC in women and particularly among premenopausal women.