420 The Role of Allostatic Load in Breast Cancer Risk: A Systematic Review ofChronic Stress and Cancer Outcomes

Abstract Aim Allostatic load, a measure of chronic stress, may influence breast cancer risk. This systematic review evaluates the relationship between allostatic load and breast cancer incidence. Method A comprehensive review of studies published from 2000 to 2024 was conducted across databases such as PubMed, Scopus, and Web of Science. Studies evaluating allostatic load’s implications on breast cancer risk were included. Data analysis utilized mixed-effects models in R to assess the correlation between allostatic load and breast cancer outcomes. Results Forty studies were included, revealing a significant association between higher allostatic load and increased breast cancer risk. Each unit increase in allostatic load was linked to a 5% increase in breast cancer risk (HR = 1.05; 95% CI: 1.03–1.07). Cohort studies indicated that women with the highest allostatic load had a 1.17-fold higher risk of developing breast cancer (HR = 1.17; 95% CI: 1.11–1.24). Conclusions This review demonstrates a strong correlation between allostatic load and breast cancer risk, suggesting that allostatic load could be a vital biomarker for early detection and risk stratification in clinical settings.