Abstract
This study investigated the relationship between the dietary antioxidant index (DAI) with pathological markers (tumor size and Ki-67 marker) and the odds of breast cancer in Iranian women. In this matched case-control study, 155 women with breast cancer and 155 cancer-free women (18-70 years old) were recruited from Iran, using a convenience sampling method. Control participants were frequency-matched to cases by 5-year age-group. DAI score was calculated based on dietary data obtained from a 168-item FFQ. Linear regression with adjustment for confounding factors was used to determine the relationship between DAI and pathological markers. Logistic regression, adjusted for confounding factors, was employed to investigate the odds ratio (OR) of breast cancer according to the quantitative and qualitative (quartiles) scores of the DAI, with 95% CI. Logistic regression subgroup according to menopausal status was also performed. A non-significant inverse relationship was observed between DAI score and Ki-67 marker in the crude model and the adjusted models 2 and 3 (p ≥ 0.05). In the crude model, in the second quartile, the odds of breast cancer was significantly reduced compared to the first quartile (OR: 0.50, CI: 0.26-0.96). However, after adjusting for confounding factors in model 2, the odds of breast cancer decreased significantly in the second and third quartiles compared to the first quartile (p < 0.05). Also, by entering the DAI as a quantitative variable in model 3 of logistic regression, a significant decrease in the odds of breast cancer was observed (p = 0.03). In the postmenopausal stage, the odds of breast cancer in the second quartile decreased significantly compared to the first quartile in the crude model. Also, in model 3, after adjusting for confounding factors, the odds ratio of breast cancer in the second and third quartiles was significantly reduced compared to the first quartile (p < 0.05). This study suggests that a higher dietary antioxidant intake, as measured by the DAI, may be associated with a lower risk of breast cancer in Iranian women and this relationship is more significant in the postmenopausal stage. These findings highlight the potential benefits of dietary antioxidants and warrant further investigation into their role in breast cancer prevention strategies.