Abstract
BackgroundWe conducted a meta-analysis to evaluate the relationship between the glutathione S-transferase μ1 (GSTM1)– and glutathione S-transferase θ1 (GSTT1)– null genotypes and susceptibility to bladder cancer.MethodsWe identified association reports from the databases of PubMed, Embase, the Cochrane Library and the China Biological Medicine Database (CBM disc) on July 1, 2017 and synthesized eligible investigations. Results were expressed using odds ratios (ORs) for dichotomous data, and we also calculated 95% confidence intervals (CIs).ResultsIn this meta-analysis, we found that the GSTM1-null genotype was associated with bladder cancer risk in the overall population, and individually in whites, Africans and Asians (overall population: OR = 1.40, 95% CI: 1.31–1.48, P<0.00001; whites: OR = 1.39, 95% CI: 1.26–1.54, P<0.00001; Africans: OR = 1.54, 95% CI: 1.16–2.05, P = 0.003; Asians: OR = 1.45, 95% CI: 1.33–1.59, P<0.00001). The GSTT1-null genotype was associated with bladder cancer risk in the overall population, but not in whites, in Africans or Asians (overall population: OR = 1.11, 95% CI: 1.01–1.22, P = 0.03; whites: OR = 1.16, 95% CI: 0.99–1.36, P = 0.07; Africans: OR = 1.07, 95% CI: 0.65–1.76, P = 0.79; Asians: OR = 1.05, 95% CI: 0.91–1.22, P = 0.51). Interestingly, a dual-null GSTM1–GSTT1 genotype was associated with bladder cancer risk in the overall population and in Asians (overall population: OR = 1.48, 95% CI: 1.15–1.92, P = 0.002; Asians: OR = 1.62, 95% CI: 1.15–2.28, P = 0.006). In conclusion, the GSTM1-null, GSTT1-null and dual-null GSTM1–GSTT1 genotypes might be associated with the onset of bladder cancer, but additional genetic-epidemiological studies should be conducted to explore this association further.
Highlights
We conducted a meta-analysis to evaluate the relationship between the glutathione S-transferase μ1(GSTM1)– and glutathione S-transferase θ1 (GSTT1)– null genotypes and susceptibility to bladder cancer
The GSTT1-null genotype was associated with bladder cancer risk in the overall population, but not in whites, in Africans or Asians
Association of the GSTM1-null genotype with bladder cancer risk. In this meta-analysis, we found that the GSTM1-null genotype was associated with bladder cancer risk in the overall population, and individually in whites, Africans and Asians
Summary
We retrieved relevant published articles from the electronic databases of PubMed, Embase, the Cochrane Library and the China Biological Medicine Database (CBM-disc) on July. Inclusion criteria (1) The endpoint of each study had to be bladder cancers. (2) The study had to include 2 comparison groups (bladder cancers vs controls). (3) The study had to provide detailed data on genotype distribution. To evaluate the quality of the recruited articles that met the above-listed inclusion criteria, we used a quality score based on 7 aspects of genetic-association studies (Additional file 1: Table S1). Two researchers who were responsible for literature retrieval appraised quality independent of one another, and a discussion was made until every respect was entirely consistent by comparison. Two investigators independently excerpted the following information from each eligible study: first author’s surname, year of publication, and number of cases and controls for both the GSTM1 and GSTT1 genotypes. We tested the consistency of the data extracted by the 2 researchers, and any disagreement was again resolved by discussion.
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