Florez-Garcia et al. 2023 — Meta-analysis of cadmium exposure and female breast cancer: pooled OR 1.13, dietary route non-significant
This random-effects meta-analysis of 17 epidemiological studies evaluates the association between cadmium exposure and female breast cancer incidence, stratifying by exposure route (dietary, airborne, biomarker-based). The pooled odds ratio across all routes is 1.13 (95% CI: 1.00, 1.28; I² = 77%), indicating a borderline elevated risk with substantial heterogeneity. When stratified by exposure route, dietary cadmium alone is not linked to elevated risk (OR: 1.05; 95% CI: 0.91, 1.21; I² = 69%), but biomarker-based studies show a non-significant elevated pooled estimate (OR: 1.37; 95% CI: 0.96, 1.94; I² = 84%). Only two of the 17 studies addressed airborne cadmium directly. No clear difference in risk by menopausal status was observed. The authors note that residual confounding by tobacco smoke constituents (a major Cd exposure route) remains a concern in interpreting the biomarker-based subgroup.
Key numbers
- Studies included in meta-analysis: 17 eligible (1 excluded for high risk of bias: self-reported cancer, insufficient covariate adjustment)
- Pooled OR, all studies: 1.13 (95% CI: 1.00, 1.28); I² = 77%
- Dietary cadmium subgroup OR: 1.05 (95% CI: 0.91, 1.21); I² = 69% (non-significant)
- Biomarker-based (urine/blood) cadmium subgroup OR: 1.37 (95% CI: 0.96, 1.94); I² = 84% (non-significant)
- Studies with airborne cadmium as primary exposure: only 2 of 17
- Literature window: studies published through October 2022
- Statistical method: random-effects meta-analysis; risk of bias assessment using pre-specified criteria
Methods (brief)
Systematic review and random-effects meta-analysis. Risk of bias assessed using set criteria. Subgroup analyses by exposure route and menopausal status. High heterogeneity (I² >69% across subgroups) limits pooled estimate precision. The dietary subgroup is the most directly relevant to food-chain Cd exposure assessment; the biomarker subgroup conflates dietary and non-dietary routes (tobacco, occupational).
Implications
Certification: Documents that dietary Cd at population-level exposures shows no statistically significant independent association with breast cancer risk in epidemiological meta-analysis (OR 1.05, CI crosses 1.0). Does not rule out a modest effect given high heterogeneity; relevant to health-effects language for Cd in HMT&C communications. Courses: Important for calibrating the dietary Cd–breast cancer narrative: pooled estimate is modest and non-significant for dietary route; the risk signal in biomarker studies is potentially confounded by tobacco, which shares dietary and non-dietary exposure pathways with Cd. App: No food-matrix concentration data. Contributes to the health-endpoints metadata for Cd. Microbiome: Not directly relevant.