Abstract
Background. The presence or absence of glutathione S-transferase M1 gene (GSTM1) and glutathione S-transferase T1 gene (GSTT1) polymorphisms, and their combined effects have been suggested as a risk factor for colorectal cancer (CRC). However, the results are inconsistent.Objectives. An updated meta-analysis was performed to solve the controversy.Methods. Meta-analyses of Observational Studies in Epidemiology (MOOSE) guidelines were used.Results. Overall, the GSTM1 null genotype was associated with an increased CRC risk in Caucasians (odds ratio (OR) = 1.14, 95% confidence interval (CI): 1.05–1.23), Asians (OR = 1.19, 95% CI: 1.08–1.32), high-quality studies (OR = 1.12, 95% CI: 1.06–1.18). Moreover, the GSTM1 null genotype was also associated with an increased colon cancer risk (OR = 1.32, 95% CI: 1.16–1.51). The GSTT1 null genotype was also associated with an increased CRC risk in Asians (OR = 1.08, 95% CI: 1.02–1.15) and Caucasians (OR = 1.24, 95% CI: 1.09–1.41). Moreover, The GSTT1 null genotype was associated with an increased rectal cancer risk (OR = 1.13, 95% CI: 1.01–1.27, I2 = 8.3%) in subgroup analysis by tumor location. Last, the GSTM1 null/GSTT1 null genotype was associated with an increased CRC risk in Asians.Conclusion. This meta-analysis indicates that the GSTM1 and GSTT1 null genotypes are associated with increased CRC risk in Asians and Caucasians, and the GSTM1 null/GSTT1 null genotype was associated with increased CRC risk in Asians.
Highlights
Colorectal cancer (CRC) is a common form of cancer, with more than 1.5 million new patients diagnosed every year worldwide [1]
The glutathione S-transferase M1 (GSTM1) null/glutathione S-transferase T1 (GSTT1) null genotype was associated with an increased colorectal cancer (CRC) risk in the overall analysis (− − vs. + +: odds ratio (OR) = 1.42, 95% confidence interval (CI): 1.17–1.73, I2 = 68.6%; − − vs. + −: OR = 1.37, 95% CI: 1.00–1.88, I2 = 73.0%; − − vs. (+ −) + (− +): OR = 1.26, 95% CI: 1.05–1.51, I2 = 70.4%; − − vs. (+ −) + (− +) + (+ +): OR = 1.26, 95% CI: 1.09–1.46, I2 = 69.0%)
In subgroup analyses by ethnicity, source of controls, and quality score, the GSTM1 null/GSTT1 null genotype was associated with an increased CRC risk in Asians
Summary
Colorectal cancer (CRC) is a common form of cancer, with more than 1.5 million new patients diagnosed every year worldwide [1]. The presence or absence of glutathione S-transferase M1 gene (GSTM1) and glutathione S-transferase T1 gene (GSTT1) polymorphisms, and their combined effects have been suggested as a risk factor for colorectal cancer (CRC). The GSTM1 null genotype was associated with an increased CRC risk in Caucasians (odds ratio (OR) = 1.14, 95% confidence interval (CI): 1.05–1.23), Asians (OR = 1.19, 95% CI: 1.08–1.32), high-quality studies (OR = 1.12, 95% CI: 1.06–1.18). The GSTT1 null genotype was associated with an increased CRC risk in Asians (OR = 1.08, 95% CI: 1.02–1.15) and Caucasians (OR = 1.24, 95% CI: 1.09–1.41). The GSTT1 null genotype was associated with an increased rectal cancer risk (OR = 1.13, 95% CI: 1.01–1.27, I2 = 8.3%) in subgroup analysis by tumor location. The GSTM1 null/GSTT1 null genotype was associated with an increased CRC risk in Asians. This meta-analysis indicates that the GSTM1 and GSTT1 null genotypes are associated with increased CRC risk in Asians and Caucasians, and the GSTM1 null/GSTT1 null genotype was associated with increased CRC risk in Asians
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