Diet Quality and All-Cause Mortality in Women with Breast Cancer from the Breast Cancer Family Registry.

Background: The impact of diet on breast cancer survival remains inconclusive. We assessed associations of all-cause mortality with adherence to the four diet quality indices: Healthy Eating Index-2015 (HEI-2015), Alternative Healthy Eating Index (AHEI), Alternative Mediterranean Diet (aMED), and Dietary Approaches to Stop Hypertension (DASH).

Methods: Dietary intake data were evaluated for 6,157 North American women enrolled in the Breast Cancer Family Registry who had been diagnosed with invasive breast cancer from 1993 to 2011 and were followed through 2018. Pre-diagnosis (n = 4,557) or post-diagnosis (n = 1,600) dietary intake was estimated through a food frequency questionnaire. During a median follow-up time of 11.3 years, 1,265 deaths occurred. Cox proportional hazards models were used to estimate multivariable-adjusted HR and 95% confidence intervals (CI).

Results: Women in the highest versus lowest quartile of adherence to the HEI-2015, AHEI, aMED, and DASH indices had a lower risk of all-cause mortality. HR (95% CI) were 0.88 (0.74-1.04; Ptrend = 0.12) for HEI-2015; 0.82 (0.69-0.97; Ptrend = 0.02) for AHEI; 0.73 (0.59-0.92; Ptrend = 0.02) for aMED; and 0.78 (0.65-0.94; Ptrend = 0.006) for DASH. In subgroup analyses, the associations with higher adherence to the four indices were similar for pre- or post-diagnosis dietary intake and were confined to women with a body mass index <25 kg/m2 and women with hormone receptor positive tumors.

Conclusions: Higher adherence to the HEI-2015, AHEI, aMED, and DASH indices was associated with lower mortality among women with breast cancer.

Impact: Adherence to a healthy diet may improve survival of women with breast cancer.