Abstract PO1-11-05: Diet quality and cardiovascular disease risk among breast cancer survivors in the Pathways Study
Authors: Ergas Isaac , Roh Janise , Kushi Lawrence , Iribarren Carlos , Nguyen-Huynh Mai , Rana Jamal , Rillamas-Sun Eileen , Laurant Cecile , Lee Valerie , Cheng Richard , Greenlee Heather , Kwan Marilyn 
Published: May 2024

Abstract
Background: While studies have shown that breast cancer survivors with healthier diets have a lower risk of non-breast cancer-specific and all-cause mortality after a breast cancer diagnosis, the relationship between diet quality and cardiovascular disease (CVD) among breast cancer survivors is not well characterized. We examined the association between diet quality at the time of breast cancer diagnosis and CVD-related outcomes in the Pathways Study, a prospective cohort of 3,415 women diagnosed with invasive breast cancer. Methods: This analysis included four diet quality indices (DQIs) consistent with healthy eating: 1. Dietary Approaches to Stop Hypertension (DASH), 2. healthy plant-based dietary index (hPDI), 3. 2015 Healthy Eating Index (HEI), 4. American Cancer Society nutrition guidelines (ACS). Each DQI was calculated from food frequency questionnaires (FFQ) at or around the time of breast cancer diagnosis, between 2005 and 2013, with a higher score representing a more healthful dietary pattern. DQI scores were categorized into quartiles with the most concordant diets in the highest quartile and the least concordant diets in the lowest quartile, for each DQI. CVD outcomes were ascertained through December 31, 2021 and included ischemic heart disease, heart failure, cardiomyopathy, stroke/transient ischemic attack, arrhythmia, cardiac arrest, valvular disease, venous thromboembolic disease and CVD-related death. Hazard ratios (HR) and 95% confidence intervals (CI) were estimated from proportional hazards regression accounting for clinical and demographic factors. Results: FFQs were completed an average 2.2 (range=0.3-7.6) months after a breast cancer diagnosis, and a total 623 (18.2%) incident CVD events and 340 (10.0%) CVD-related deaths were ascertained over 39,263 person-years of follow-up. Participants in the highest quartile of the DASH DQI had substantially reduced risks of heart failure (HR=0.50, 95% CI 0.31-0.81), arrhythmia (HR=0.76, 95% CI 0.62-0.93), cardiac arrest (HR=0.75, 95% CI 0.60-0.93), valvular disease (HR=0.77, 95% CI 0.62-0.96), venous thromboembolic disease (HR=0.74, 95% CI 0.59-0.92), and a 33% reduced risk of CVD-related death (HR=0.67, 95% CI 0.48-0.95) relative to those in the lowest quartile. Tests for trend across quartiles of the DASH DQI were also statistically significant at a p-value &lt; 0.03. The only notable association found in the other three DQIs was between hPDI and lower risk of heart failure (HR=0.61, 95% CI 0.39-0.95) in women in the highest quartile compared to the lowest quartile (Table 1). Summary: These findings suggest that diets concordant with DASH and hPDI dietary patterns, may be beneficial for preventing CVD and CVD-related death after a breast cancer diagnosis.
Table 1. Cox proportional hazard ratios and 95% confidence intervals for quartiles of diet quality indices and CVD events and CVD-related death
Citation Format: Isaac Ergas, Janise Roh, Lawrence Kushi, Carlos Iribarren, Mai Nguyen-Huynh, Jamal Rana, Eileen Rillamas-Sun, Cecile Laurant, Valerie Lee, Richard Cheng, Heather Greenlee, Marilyn Kwan. Diet quality and cardiovascular disease risk among breast cancer survivors in the Pathways Study [abstract]. In: Proceedings of the 2023 San Antonio Breast Cancer Symposium; 2023 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2024;84(9 Suppl):Abstract nr PO1-11-05.