Association Between Cd Exposure and Risk of Prostate Cancer: A PRISMA-Compliant Systematic Review and Meta-Analysis

Abstract

Several observational studies on the association between Cd exposure and risk of prostate cancer have yielded inconsistent results. To address this issue, we conducted a meta-analysis to evaluate the correlation between Cd exposure and risk of prostate cancer.Relevant studies in PubMed and Embase databases were retrieved until October 2015. We compared the highest and lowest meta-analyses to quantitatively evaluate the relationship between Cd exposure and risk of prostate cancer. Summary estimates were obtained using a random-effects model.In the general population, high Cd exposure was not associated with increased prostate cancer (OR 1.21; 95% CI 0.91-1.64), whereas the combined standardized mortality ratio of the association between Cd exposure and risk of prostate cancer was 1.66 (95% CI 1.10-2.50) in populations exposed to occupational Cd. In addition, high D-Cd intake (OR 1.07; 95% CI 0.96-1.20) and U-Cd concentration (OR 0.86; 95% CI 0.48-1.55) among the general population was not related to the increased risk of prostate cancer. In the dose analysis, the summary relative risk was 1.07 (95% CI 0.73-1.57) for each 0.5 μg/g creatinine increase in U-Cd and 1.02 (95% CI 0.99-1.06) for each 10 μg/day increase of dietary Cd intake. However, compared with nonoccupational exposure, high occupational Cd exposure may be associated with the increased risk of prostate cancer.This meta-analysis suggests high Cd exposure as a risk factor for prostate cancer in occupational rather than nonoccupational populations. However, these results should be carefully interpreted because of the significant heterogeneity among studies. Additional large-scale and high-quality prospective studies are needed to confirm the association between Cd exposure and risk of prostate cancer.

FIGURE 1

Flow diagram of the literature search and study selection.

FIGURE 2

Forest plot of Cd exposure and prostate cancer risk (SMR) in occupational Cd exposure population. Cd = cadmium, SMR = standardized mortality ratio.

FIGURE 3

Funnel plot of Cd exposure and prostate cancer risk (SMR) in occupational Cd exposure population. Cd = cadmium, SMR = standardized mortality ratio.

FIGURE 4

Forest plot of Cd exposure and prostate cancer risk (OR) in occupational/environmental Cd exposure population. Cd = cadmium, OR = odds ratio.

FIGURE 5

Funnel plot of Cd exposure and prostate cancer risk (OR) in occupational/environmental Cd exposure population. Cd = cadmium, OR = odds ratio.

FIGURE 6

Forest plot of linear trend between dietary Cd intake and risk of prostate cancer (RR), with dose scale of 10 μg/d increase in environmental Cd exposure population. Cd = cadmium, RR = relative risk.