title: [Glutathione S-transferase M1 polymorphism and the risk on colorectal cancer: a multilevel meta regression].
abstract: OBJECTIVE
  In order to investigate the relationship between Glutathione S-transferase M1 (GSTM1) status and the risk on colorectal cancer as well as to detect the related factors to this association.
  
  
  METHODS
  A pooled analysis of multilevel Meta-regression was performed to estimate GSTM1 deficiency associated with the risks of colorectal cancer. Then subgroup Meta-regression was undertaken to evaluate the possible relationship between heterogeneity and the related characteristics.
  
  
  RESULTS
  The overall pooled odds ratios of colorectal cancer risk associated with GSTM1 deficiency was 1.17 (95% CI: 1.08-1.26). Ethnicity, percent of GSTM1 deficiency in population had significant relationships with heterogeneity across the studies (P < 0.05). Results of subgroup Meta-regression showed that GSTM1 deficiency was significantly associated with colorectal cancer risk in ethnic subgroups of Asians, Caucasians and in low level (lower than 50%) of GSTM1 deficiency population (P < 0.05). The respective pooled ORs were 1.14, 1.25 and 1.29.
  
  
  CONCLUSIONS
  GSTM1 deficiency seemed to be a risk factor for colorectal cancer, while interactions on the characteristics of ethnicity, percentage of GSTM1 deficiency in the studied population were related to this association.
authors: Department of Epidemiology and Health Statistic, School of Medicine, Zhejiang University, Hangzhou 310031, China.
authors: Han-Qing
authors: HQ
authors: He
authors: Kun
authors: K
authors: Chen
authors: Yang
authors: Y
authors: Zhang
authors: Feng
authors: F
authors: Tong
authors: Chun-Hong
authors: CH
authors: Fan
authors: Liang
authors: L
authors: Song