Association between Dietary Cadmium Exposure and Breast Cancer Risk: An Updated Meta-Analysis of Observational Studies

BACKGROUND: Diet is the primary way cadmium (Cd) enters the body in those without occupational exposure and who do not inhabit Cd-polluted regions. Findings on the relationship between dietary Cd exposure and breast cancer (BC) risk have been inconsistent; a meta-analysis has supported this association but 2 recent cohort studies showed inconsistent results. Hence, we performed an updated meta-analysis to re-evaluate the association between dietary Cd exposure and BC risk. MATERIAL/METHODS: We searched PubMed, Medline, and EMBASE to identify relevant studies published through September 2014. Combined relative risks (RRs) and the corresponding 95% confidence intervals (CIs) were used to assess the association between dietary Cd exposure and BC risk. RESULTS: We identified 6 studies involving 321 315 participants and 11 978 cases. Our study suggested there was no statistically significant positive association between dietary Cd exposure and BC risk, the combined RR and corresponding 95% CI was 1.01 [0.88, 1.14]. The result was not modified by menopause status, geographic area, or study design. CONCLUSIONS: Our study did not find a statistically significant positive association between dietary Cd exposure and BC risk. It is necessary to investigate this relationship among the high-risk groups and more cohort studies based on diverse populations are needed.