Association of cadmium and lead exposure with mortality in cancer survivors: A prospective cohort study

Lead and cadmium are well-documented for their carcinogenic properties and their potential to induce cellular malignancy. Nevertheless, there is a paucity of research examining the correlation between blood cadmium and lead levels and the prognostic outcomes of cancer survivors. This study aims to investigate the relationship between blood concentrations of these heavy metals and both overall and site-specific cancer mortality risks among cancer survivors. We identified mortality rates and specific causes of death among cancer survivors by using National Health and Nutrition Examination Survey mortality data. To assess mortality outcomes, we employed multivariable Cox regression analyses, generating hazard ratios (HR) and 95 % confidence intervals (CI). We used Kaplan-Meier survival curves and restricted cubic spline models to further examine these associations. We conducted subgroup analyses to observe the prognostic risks associated with high concentrations of these metals across various tumor categories. This study revealed a significant positive correlation between whole blood cadmium concentration and all-cause mortality in cancer survivors, yielding a hazard ratio (HR) of 1.73 (95 % CI: 1.39-2.16). Elevated blood cadmium levels were significantly linked to increased cancer-specific mortality, with an HR of 2.72 (95 % CI: 1.73-4.26). A notable positive association was found between blood lead and cancer-specific mortality (HR = 1.83, 95 % CI: 1.13-2.97). Subgroup analyses indicated that elevated blood cadmium levels were significantly correlated with increased mortality risk in patients with skin and soft tissue cancers, whereas high blood lead levels were significantly associated with greater mortality risk in patients with reproductive system cancers. Additionally, elevated levels of both blood lead and cadmium were significantly related to a marked increase in mortality risk among patients with lung and mediastinal malignancies. In conclusion, our study indicates a positive correlation between increased whole blood cadmium concentrations and both all-cause and cancer-specific mortality among cancer survivors.