Dietary inflammatory index and quality of life in patients with breast cancer: a cross-sectional study

Abstract

Background Breast cancer survivorship is frequently accompanied by impaired quality of life (QoL). Diet-related systemic inflammation may influence physical, emotional, and psychological well-being, yet evidence linking the inflammatory potential of diet to QoL in women with breast cancer remains limited. Methods In this cross-sectional study, 600 women with confirmed breast cancer were recruited from the Isfahan Breast Cancer Registry between 2021 and 2023. Dietary intake and lifestyle characteristics were collected through structured telephone interviews. The Dietary Inflammatory Index (DII (R)) and energy-adjusted DII (E-DII (TM)) were calculated, and QoL was assessed using a five-point Likert scale. Associations of DII and E-DII with QoL were examined using multivariable linear regression with adjustment for potential confounders. Quartile-based analyses and tests for linear trend were also performed. Results Higher DII scores were associated with lower QoL in adjusted models (beta = -0.12; 95 CI: -0.16 to - 0.08; p < 0.001), with a clear linear decline in QoL across increasing DII quartiles (p for trend < 0.001). E-DII was similarly inversely associated with QoL (beta = -0.06; 95 CI: -0.11 to - 0.02; p = 0.007), and a consistent trend across E-DII quartiles was observed (p for trend = 0.01). Discussion Diets with greater pro-inflammatory potential were associated with poorer QoL among women with breast cancer. Although the cross-sectional design precludes causal inference, these findings support the hypothesis that anti-inflammatory dietary strategies may be a relevant target in survivorship care and justify longitudinal and interventional studies to clarify directionality and clinical impact.