Glutathione S-transferase M1 null genotype related to poor prognosis of colorectal cancer

Published studies showed controversial findings about the relationship between glutathione S-transferase M1 (GSTM1) null genotype and clinical outcomes of patients with colorectal cancer. We performed a meta-analysis to quantitatively assess the association between GSTM1 null genotype and prognosis of patients with colorectal cancer. We systematically searched Pubmed, Embase, and Web of Science to identify prospective or retrospective cohort studies assessing the association of GSTM1 null genotype with overall survival (OS) or disease-free survival (DFS) in colorectal cancer. The hazard ratios (HRs) and 95 % confidence intervals (95 % CIs) were used to assess the association of GSTM1 null genotype with OS or DFS. Finally, 15 studies from 14 publications with 4326 colorectal cancer patients were included into the meta-analysis. There was no heterogeneity in the meta-analysis relating OS (I (2) = 0 %) and DFS (I (2) = 0 %). Overall, GSTM1 null genotype was significantly associated with poor OS in patients with colorectal cancer (HR = 1.18, 95 % CI 1.07-1.30, P = 0.001). In addition, GSTM1 null genotype was also significantly associated with poor DFS in patients with colorectal cancer (HR = 1.15, 95 % CI 1.03-1.28, P = 0.015). No obvious risk of publication bias was observed. GSTM1 null genotype is significantly associated with poor OS and DFS in patients with colorectal cancer, which suggests that GSTM1 null genotype confers poor effect on the prognosis of colorectal cancer.