Research Article Better Postdiagnosis Diet Quality Is Associated with Reduced Risk of Death among Postmenopausal Women with Invasive Breast Cancer in theWomen's Health Initiative

Background: Few studies have evaluatedwhether adherence to dietary recommendations is associatedwith mortality among cancer survivors. In breast cancer survivors, we examined howpostdiagnosis Healthy Eating Index (HEI)-2005 scores were associated with all-cause and cause-specific mortality. Methods: Our prospective cohort study included 2,317 postmenopausal women, ages 50 to 79 years, in the Women’s Health Initiative’s Dietary Modification Trial (n 1,205) and Observational Study (n 1,112), who were diagnosed with invasive breast cancer and completed a food frequency questionnaire after being diagnosed. We followed women from this assessment forward. We used Cox proportional hazards models to estimate multivariate-adjusted HRs and 95 % confidence intervals (CI) for death from any cause, breast cancer, and causes other than breast cancer, according to HEI-2005 quintiles. Results:Over 9.6 years, 415 deaths occurred. After adjustment for key covariates, women consuming better qualitydiets hada 26 % lower risk of death fromany cause (HRQ4:Q1, 0.74; 95%CI, 0.55–0.99;Ptrend 0.043) anda 42 % lower risk of death from non–breast cancer causes (HRQ4:Q1, 0.58; 95 % CI, 0.38–0.87; Ptrend 0.011). HEI-2005 score was not associated with breast cancer death (HRQ4:Q1, 0.91; 95 % CI, 0.60–1.40; Ptrend 0.627). In analyses stratifiedby tumor estrogen receptor (ER) status, better diet qualitywas associatedwith a reduced risk of all-cause mortality among women with ERþ tumors (n 1,758; HRQ4:Q1, 0.55; 95 % CI, 0.38–0.79; Ptrend 0.0009). Conclusion: Better postdiagnosis diet quality was associated with reduced risk of death, particularly from non–breast cancer causes. Impact: Breast cancer survivors may experience improved survival by adhering to U.S. dietary guidelines. Cancer Epidemiol Biomarkers Prev; 23(4); 575–83. 2014 AACR