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

Abstract

Few studies have evaluated whether adherence to dietary recommendations is associated with mortality among cancer survivors. In breast cancer survivors, we examined how postdiagnosis Healthy Eating Index (HEI)-2005 scores were associated with all-cause and cause-specific mortality. 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. Over 9.6 years, 415 deaths occurred. After adjustment for key covariates, women consuming better quality diets had a 26% lower risk of death from any cause (HRQ4:Q1, 0.74; 95% CI, 0.55-0.99; Ptrend = 0.043) and a 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 stratified by tumor estrogen receptor (ER) status, better diet quality was associated with a reduced risk of all-cause mortality among women with ER(+) tumors (n = 1,758; HRQ4:Q1, 0.55; 95% CI, 0.38-0.79; Ptrend = 0.0009). Better postdiagnosis diet quality was associated with reduced risk of death, particularly from non-breast cancer causes. Breast cancer survivors may experience improved survival by adhering to U.S. dietary guidelines.