Adherence to Dietary Recommendations among Long-Term Breast Cancer Survivors and Cancer Outcome Associations

Abstract

Background: Adherence to dietary recommendations has been shown to be associated with reduced mortality in healthy populations. Little is known about the possible benefits of adherence to dietary recommendations among breast cancer survivors. Methods: Dietary information was collected using food frequency questionnaires at the 5-year postdiagnosis survey in 3,450 5-year breast cancer survivors from the Shanghai Breast Cancer Survival Study. Adherence scores to Chinese Food Pagoda (CHFP)-2007, CHFP-2016, modified Dietary Approaches to Stop Hypertension (DASH) and Healthy Eating Index 2015 (HEI-2015) were created. Cox proportional hazards models were used to estimate hazard ratios (HR) and 95% confidence intervals (CIs) for total mortality and breast cancer specific events according to adherence scores. Results: Participants in the highest quartiles of CHFP-2007, CHFP-2016 and DASH had 25-34% lower risk of total mortality (HR=0.66, 95%CI: 0.48 to 0.89 for CHFP-2007; HR=0.75, 95%CI: 0.55 to 1.01 for CHFP-2016; HR=0.66, 95%CI: 0.49 to 0.91 for DASH), and 36-40% lower risk of breast cancer specific events (HR=0.64, 95%CI: 0.44 to 0.93 for CHFP-2007; HR=0.67, 95%CI: 0.45 to 0.99 for CHFP-2016; HR=0.60, 95%CI: 0.40 to 0.90 for DASH) comparing to the lowest quartiles. Associations did not vary by known prognostic factors. HEI-2015 scores were not significantly associated with breast cancer outcomes. Conclusion: Higher adherence to CHFP and DASH dietary guidelines post-cancer diagnosis was associated with reduced risk of both overall death, and breast cancer specific recurrence or death among long-term breast cancer survivors. Impact: Our study highlights the importance of overall dietary quality among long-term breast cancer survivors.