Abstract B100: Index-based dietary patterns and risk of breast cancer in postmenopausal women in the NIH-AARP Diet and Health Study

Abstract

Abstract Background: Because foods and nutrients could have synergistic or antagonistic effects when they are consumed in combination, dietary patterns in relation to diseases are a growing interest. Index-based dietary patterns that are created based on recommended dietary guidelines and Mediterranean Diet Score have been related to lower risk of some diseases. Objectives: We examined Healthy Eating Index 2005 (HEI), Alternative Healthy Eating Index (AHEI), and Alternative Mediterranean Diet Score (AMED) were associated with breast cancer risk. We also investigated the association by hormone receptor status of breast cancer. Methods: The NIH-AARP Diet and Health Study consisted of 184,932 postmenopausal women aged 50–71 years at baseline and followed them from 1995 to 2006. The scores for each dietary pattern was calculated based on intakes assessed by a 124-items food frequency questionnaire. Cancer cases were ascertained through state cancer registries. Thirty nine percent of breast cancer cases had information on hormone receptor status. Cox Proportional hazard model, with person-years as the underlying time metric, was used to estimate the relative risk (RR) and 95% confidence intervals (CI), adjusting for potential breast cancer risk factors. Results: During an average nine year follow up, 7,182 incident invasive breast cancer cases were identified. Both HEI and AHEI were inversely associated with risk of breast cancer. Compared with the lowest quintile of HEI, RR for the highest quintile was 0.91 (95% CI: 0.84–0.98 p-trend=0.01). RR for the highest quintile of AHEI vs. the lowest was 0.92 (95% CI: 0.85–1.00, p-trend=0.04). The AMED was also related to lower risk of breast cancer. Compared with women with low AMED score (0–3), women with high AMED score (7–9) had 10% lowered risk of breast cancer (RR: 0.90, 95% CI: 0.82–0.99, p-trend=0.01). Although it was not statistically significant, the association of index-based dietary patterns with risk of ER− was slightly stronger than those with ER+. RR for the highest quintile of HEI vs. the lowest was 0.70 (95% CI: 0.52–0.95, p-trend=0.12, n=459 cases) for ER− breast cancer and 0.95 (95% CI: 0.83–1.09, p-trend=0.30, n=2,322 cases) for ER+ breast cancer. In contrast, the highest AMED score vs. the lowest was 0.87 (95% CI: 0.73–1.03, p-trend=0.16) for ER+ and 0.91 (95% CI: 0.62–1.31, p-trend=0.26) for ER− cases. Conclusion: Dietary patterns based on Dietary Guidelines for Americans or Mediterranean diet were related to a lower risk of breast cancer in postmenopausal women. Citation Information: Cancer Prev Res 2011;4(10 Suppl):B100.