Adherence to HEI-2010 and odds of breast cancer according to the menopause status: Evidence from Middle Eastern Country

Background
Majority of earlier studies have assessed the association between individual healthy eating index-2010 (HEI-2010) and the odds of breast cancer (BC). However, no study has been conducted on the effect of compliance with HEI-2010 and the odds of BC in the Iranian population with a large sample size. Therefore, we aimed to investigate the relationship between the HEI-2010 and the odds of BC in the Iranian population.

Method
This population-based case-control study included 350 newly diagnosed cases of BC and 700 healthy controls randomly selected from adult women. HEI-2010 was examined using validated questionnaires. The adherence to HEI-2010 among the participants was divided into four categories. The general characteristics of the participants in the quartiles of the HEI score for categorical variables and continuous variables were evaluated using chi-square and one-way analysis of variance, respectively. Also, using logistic regression analysis, dietary intakes were evaluated in HEI score quartiles. Also, confounding variables were adjusted in different models.

Result
People with the highest HEI score had 60% lower odds of BC (OR: 0.40; 95% CI: 0.27, 0.57) than those with the lowest score among post-menopause women. After controlling for age and energy intake, individuals with the highest HEI score were 78% less likely to have BC compared with those with the lowest score (OR: 0.22; 95% CI: 0.14, 0.33). Adjustments for other potential confounders including demographic factors made the association stronger (OR: 0.21; 95% CI: 0.13, 0.32). This association remained significant even after taking BMI into model (OR: 0.27; 95% CI: 0.17, 0.43).

Conclusion
Finally, in this study we found an association between HEI-2010 and odds of breast cancer. This association was particularly seen in postmenopausal women. No significant association was found between adherence to HEI-2010 and odds of BC among pre-menopausal.