Abstract PS1-04-25: Associations of Diet Quality with Symptom Severity and Functioning During Breast Cancer Treatment in American and Taiwanese Patients

Abstract Background and Objective: Breast cancer (BC) patients undergoing curative treatment commonly experience appetite loss and subsequent poor dietary quality. The role of nutrition in symptom burden and functioning during treatment remains inadequately studied among BC patients. This study examined these associations among breast cancer patients and whether the associations varied across different cultural dietary practices. Methods and Analysis: Cross-sectional data from 81 American (non-Hispanic White, Black, Hispanic) and 81 Taiwanese female BC patients receiving primary treatment (e.g., surgery, chemotherapy, and/or radiation) were collected. Participants were diagnosed between 2021 and 2024 with stage 0-III primary BC and enrolled within six months of diagnosis. Dietary intake was assessed using an automated 24-hour recall tool (ASA24) on three randomly selected days. Diet quality was assessed by the Healthy Eating Index (HEI-2020) through four categories: ‘good’ (80-100), ‘needs improvement’ (70-79), ‘poor’ (60-69), or ‘very poor’ (0-59). A good quality diet refers to an adequate intake of healthy foods (e.g., fruits, vegetables, whole grains, dairy, protein foods, and fatty acids), and a limited intake of undesirable dietary components (e.g., refined grains, sodium, added sugars, and saturated fat). Poor-quality diets suggest an insufficient intake of healthy foods and an excess intake of undesirable components. Patient-reported symptoms (e.g., insomnia, fatigue, appetite loss, and diarrhea) and functional outcomes (e.g., physical, emotional, social, and role functioning) were measured via EORTC QLQ-BR30. Linear regression examined the associations of HEI and subcomponent scores with each study outcome, adjusting for nationality, age, cancer stage, treatment type, body mass index, calorie intake, physical activity, and financial difficulties. Appetite loss was included in all regression models as a confounder, except when it was a symptom outcome. Results: Only 11% of the sample (Americans: 7%, Taiwanese: 4%) had good diet quality. Over 68% had poor diet quality. A higher percentage of Americans (25%) than Taiwanese (13%) had very poor diets. Americans had higher intakes of added sugar and saturated fat, while Taiwanese had higher intakes of sodium (p < 0.001). However, nationality was not a predictor of the outcomes. The overall HEI scores were not associated with any study outcomes. Patients with more severe appetite loss reported higher total fruit intake (β = 3.21, 95% CI: 0.32, 6.09). Total vegetable intake was inversely associated with insomnia (β = -5.12, 95% CI: -10.1, -0.13). Higher seafood and plant protein intake was associated with a higher prevalence of diarrhea (β = 3.44, 95% CI: 0.37, 6.51), and higher saturated fat intake was associated with poorer physical functioning (β = -1.11, 95% CI: -2.16, -0.07). Conclusion: Most patients undergoing BC treatment had poor diet quality. These cross-sectional findings do not establish causation; however, we noted certain dietary characteristics with specific symptoms. Longitudinal investigations in a larger sample will be needed to further evaluate these observed associations to inform dietary recommendations for BC patients during treatment. Citation Format: R. Tran, Y. Liu, C. Huang, K. Chang, F. Hsiao, T. Fung, C. Lo, W. Kuo, G. Sander, R. J. Wong, K. N. Hitesman, M. Thomas, J. Chen, S. Jeong, M. Tan, J. H. Wang. Associations of Diet Quality with Symptom Severity and Functioning During Breast Cancer Treatment in American and Taiwanese Patients [abstract]. In: Proceedings of the San Antonio Breast Cancer Symposium 2025; 2025 Dec 9-12; San Antonio, TX. Philadelphia (PA): AACR; Clin Cancer Res 2026;32(4 Suppl):Abstract nr PS1-04-25.