Breast Cancer Frequency and Exposure to Cadmium: A Meta- Analysis and Systematic Review

Background: In this meta-analysis we review evidence suggesting that exposure to cadmium is a cause ofbreast cancer. Materials and
Methods: We conducted Medline/PubMed and Scopus searches using selectedMeSH keywords to identify papers published from January 1, 1980 through January 1, 2013. Data weremerged and summary mean differences were estimated using either a random-effects model or a fixed-effectsmodel.
Results: There were 13 studies including 978 exposed cases and 1,279 controls. There was no statisticallysignificant difference in the frequencies of breast cancer between cadmium-exposed and control groups, and thesummary estimate of mean difference was 0.71 (95%CI: 0.33-1.08). However, stratification showed that therewere statistically significant differences in the frequencies of breast cancer between cadmium-exposed and controlgroups among Asian compared with Caucasian population, and the summary estimates of mean difference were1.45 (95%CI: 0.62-2.28) vs. 0.25 (95%CI: -0.09-0.6), respectively. There was a difference in the frequencies ofbreast cancer between cadmium-exposed and control groups in peripheral venous blood sampling methods,and the summary estimate of mean difference was 1.41 (95%CI: 0.46-2.37).
Conclusions: Data indicate that thefrequencies of breast cancer might be an indicator of early genetic effects for cadmium-exposed populations.However, our meta-analysis was performed on population-based studies; meta-analysis based on individualdata might provide more precise and reliable results. Therefore, it is necessary to construct an internationaldatabase on genetic damage among populations exposed to cadmium that may contain all raw data of studiesexamining genetic toxicity.