2,3,7,8-Tetrachlorodibezo-p-dioxin exposure and prostate cancer: a meta-analysis of cohort studies

ObjectiveTo perform a meta-analysis of cohort studies and evaluate the association between exposure to 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) and prostate cancer quantitatively.Study designPublications before April 2012 about populations exposed to TCDD were searched in PubMed. Only cohort studies were included. Extraction and quality assessment of included articles was performed independently by two authors using the MOOSE guidelines.MethodsA total of 17 cohort studies on prostate cancer with information about standardized mortality ratios (SMR), risk ratio (RR), standardized incidence ratios (SIR) and TCDD exposure were included. SMRs and RRs were pooled separately after weighing each study by calculating the inverse of the estimated variance.ResultsBased on the 13 reported SMRs or SIRs, the meta-analysis yielded a meta-SMR of 1.26 (95% confidence interval 1.00–1.57, P = 0.046). The meta-RR, based on four reported RR from four cohorts, was 1.04 (95% confidence interval 0.85–1.28). Begg's funnel plot showed little evidence of publication bias (Egger's test P-value = 0.817).ConclusionThis meta-analysis suggests that exposure to TCDD is associated with increased risk of prostate cancer.