The association between diet-associated inflammation and breast cancer: findings from an Iranian case-control study

Background: Breast cancer (BrCa) is the most common cancer among women worldwide and is the second leading cause of cancer-related death in women, after lung cancer, in developed countries. This cancer is among the top five most common cancers in Iran and ranks first among cancers diagnosed in women. Studies have shown that dietary components are implicated in the etiology of BrCa. Also, the existence of molecular connections between inflammation pathways and BrCa has been demonstrated via anumber of different bimolecular events. Methods: We examined the ability of the dietary inflammatory index (DIITM) to predict the risk of BrCa in a case-control study conducted from March 2015 to February 2016. Thisincluded 145 cases and 148 controls, who attended the Shahid Beheshti University of Medical Sciences Cancer Research Center. DII scores were computed based on dietary intake assessed using a validated 168-item FFQ. Logistic regression models were used to estimate multivariable ORs adjusted age, energy, education, exercise, BMI, smoking, family history of cancer, age at menarche, parity, marital status, menopausal status, oral contraceptive use and hormone replacement therapy.Results: Results obtained from modeling DII as a continuous variable in relation to risk of BrCa showed a positive association after adjustment for age and energy (OR=1.76; 95% CI=1.43-2.18); and were nearly identical in the multivariable analyses (OR=1.80; 95% CI=1.42-2.28). When analyses were carried out with DII expressed as tertiles, and adjusting for age and energy, subjects in tertile 3 had an OR of 6.94 (95% CI= 3.26-14.79; P-trend ≤0.0001) in comparison to subjects in tertile 1. After multivariable adjustment, results were essentially identical as in the model adjusting only for age (OR tertile 3vs1=7.24; 95% CI=3.14-16.68; P-trend ≤0.001). Sub group analyses revealed similar positive associations with HER 2 receptor +ve, progesterone receptor +ve, estrogen receptor +ve and lymph node invasive cases.Conclusion: Subjects who consumed a more pro-inflammatory diet were at increased risk of BrCa compared to those who consumed a more anti-inflammatory diet.

Keywords:

Breast Cancer , Inflammation , Dietary Inflammatory Index (DII) , Nutritional Assessment