Insulinemic potential of diet and risk of total and subtypes of breast cancer among US females.
Academic Article
Overview
abstract
BACKGROUND: Insulin resistance and hyperinsulinemia play important roles in the progression of multiple chronic disease and conditions. Diet modulates insulin response; however, evidence is limited regarding whether diets with higher insulinemic potential increase risk of invasive breast cancer. OBJECTIVES: We aimed to prospectively evaluate the association between a food-based empirical dietary index for hyperinsulinemia (EDIH) and the incidence of invasive breast cancer. METHODS: We prospectively followed 76,686 females from the Nurses' Health Study (NHS, 1984-2016) and 93,287 females from the Nurses' Health Study II (NHSII, 1991-2017). Diet was assessed by food frequency questionnaires every 4 years. The insulinemic potential of diet was evaluated using the previously established EDIH based on circulating C-peptide concentrations. Higher scores indicate higher insulinemic potential of the diet. Covariates included reproductive, hormonal, and anthropometric factors (height and BMI at age 18 years), race, socioeconomic status, total alcohol intake, total caloric intake, and physical activity. RESULTS: During 4,216,106 person-years of follow-up, we documented 10,602 breast cancer cases (6,689 NHS; 3,913 NHSII). In the pooled multivariable-adjusted analyses, females in the highest, compared with the lowest, EDIH quintile were at higher breast cancer risk (HRQ5vsQ1=1.15; 95% CI 1.07, 1.24; P-trend<0.01). Although heterogeneity by estrogen receptor (ER) status was non-significant, the strongest association between EDIH and breast cancer was observed for ER-negative tumors (HRQ5vsQ1=1.21; 95% CI 1.00, 1.46; P-trend=0.02). Among tumor molecular subtypes, the strongest associations were observed for human epidermal growth factor receptor 2 (HER2)-enriched tumors (HRQ5vsQ1=1.62; 95% CI 1.01, 2.61; P-trend=0.02). CONCLUSIONS: A dietary pattern contributing to hyperinsulinemia and insulin resistance was associated with greater breast cancer risk, especially ER-negative and HER2 enriched tumors. Our findings suggest that dietary modifications to reduce insulinemic potential may reduce risk of breast cancer.
