The mediation role of allostatic load/chronic stress on the relationship between cancer survivorship and cardiovascular disease mortality

Background: Cancer survivors face an elevated risk of cardiovascular disease (CVD) and cardiovascular disease mortality (CVDm) compared to the general population. Allostatic load (AL), a composite score reflecting cardiovascular, metabolic, and immune markers, assesses the cumulative impact of chronic stress and life events. Increased AL in cancer patients is linked to up to a 30 % higher CVD risk. We hypothesized that cancer diagnosis and therapy contribute to increased AL, mediating the association between cancer survivorship and CVDm. Methods: This retrospective cohort study analyzed National Health and Nutrition Examination Survey (NHANES) data linked with the National Death Index (NDI) from 1988 to 2019. Cancer survivorship (yes vs. no), AL, and CVDm were the exposure, mediator, and outcome variables, respectively. Mediation analyses adapted to survival outcomes were performed. Results: Among 14,416 participants, cancer survivors <65 years-old exhibited a 41 % higher associated CVDm risk. High AL mediated 5.4 %, 8.9 %, and 3.6 % of the effect for all adults, 18–64 years, and ≥65 years, respectively. Black patients <65 years-old had an 84 % higher associated CVDm risk, with AL mediating 9.2 %, 5.8 %, and 12.6 % for all adults, 18–64 years, and ≥65 years, respectively. White patients showed a 20 % higher associated CVDm risk, with AL mediating 4.4 %, 2.8 %, and 5.7 % for all adults, 18–64 years, and ≥65 years, respectively. Conclusions: Increased CVDm risk among cancer survivors, particularly in Black individuals, is associated with higher AL mediation. These disparities may stem from social determinants of health.