Allostatic load predicts symptom burden among breast cancer survivors

Breast cancer survivors frequently experience persistent and co-occurring symptoms, yet the role of allostatic load (AL), a measure of cumulative physiological stress, in shaping these outcomes remains unclear. We examined the associations of AL with physical and mental health outcomes, symptom burden profiles, and socioeconomic disparities among breast cancer survivors using data from the UK Biobank. The study included 1444 breast cancer survivors and 1444 age-matched women without cancer who completed baseline (2006–2010) and follow-up (2022) assessments. AL was derived from 11 biomarkers and analyzed as a continuous measure. Survivorship outcomes included sleep quality, fatigue, depression, anxiety, cognitive function, functional limitation, and self-rated mental health. Latent class analysis was used to identify symptom burden profiles, and multivariable regression and mediation analyses were performed. Among breast cancer survivors (mean age 58 years), higher AL was associated with poorer sleep quality (β = 0.18, 95% CI 0.06–0.29), greater fatigue (β = 0.23, 95% CI 0.12–0.35), increased functional limitation (β = 0.28, 95% CI 0.09–0.47), higher depressive symptoms (β = 0.15, 95% CI 0.02–0.28), higher anxiety (β = 0.12, 95% CI 0.01–0.23), and poorer self-rated mental health (β = −0.09, 95% CI −0.13 to −0.05), but not cognitive function. These associations were weaker or absent among women without cancer. Higher AL was also associated with increased likelihood of adverse symptom burden profiles. Mediation analyses indicated that AL partially mediated associations of income and education with multiple outcomes, accounting for approximately 6–15% and 8–9% of these associations, respectively. These findings suggest that elevated AL is associated with worse survivorship outcomes and contributes to socioeconomic disparities in symptom burden among breast cancer survivors. Chronic physiological stress may represent an important mechanism underlying survivorship heterogeneity and a potential target for intervention.