Purpose: The glutathione S-transferase M1 (GSTM1) as a member of phase II detoxification enzymes is expressed in many tissues and plays a critical role in preventing the occurrence of cancer. Published data regarding the associations between the GSTM1 polymorphism and colorectal cancer (CRC) risk are inconclusive.
Materials and methods: A meta-analysis of 55 case-control studies involving 17,498 cases and 26,441 controls were performed to assess the strength of association using odds ratio (OR) with 95% confidence interval (CI).
Results: The meta-analysis of those studies suggested that GSTM1 null genotype was significantly associated with CRC risk (OR = 1.13, 95% CI = 1.06-1.20, P < 0.0001). In the subgroup analysis by ethnicity, significant risks were associated with GSTM1 null genotype in Caucasians (OR = 1.18, 95% CI = 1.07-1.29, P = 0.001), Asians (OR = 1.11, 95% CI = 1.02-1.22, P = 0.02), and mixed group (OR = 1.01, 95% CI = 0.90-1.14, P = 0.85). In the subgroup analysis by study design, significant elevated risks were associated with GSTM1 null genotype in hospital-based case-control study group (OR = 1.20, 95% CI = 1.10-1.31, and P < 0.0001) but not in population-based case-control study group (OR = 1.03, 95% CI = 0.96-1.10, P = 0.43).
Conclusions: Based on our meta-analysis, the GSTM1 null genotype is a risk factor for CRC.
Keywords: Colorectal cancer; glutathione S-transferase M1; meta-analysis; polymorphism.