Meta-analysis and pooled analysis of GSTM1 and CYP1A1 polymorphisms and oral and pharyngeal cancers: A HuGE-GSEC review

The association of GSTM1 and CYP1A1 polymorphisms and oral and pharyngeal cancers was assessed through a meta-analysis of published case-control studies and a pooled analysis of both published and unpublished case-control studies from the Genetic Susceptibility to Environmental Carcinogens database (http://www.upci.upmc.edu/research/ccps/ccontrol/index.html). Thirty publications used in the meta-analysis included a total of 7783 subjects (3177 cases and 4606 controls); 21 datasets, 9397 subjects (3130 cases and 6267 controls) were included in the pooled analysis. The GSTM1 deletion was 2-fold more likely to occur in African American and African cases than controls (odds ratio: 1.7, 95% confidence interval: 0.9-3.3), although this was not observed among whites (odds ratio: 1.0, 95% confidence interval: 0.9-1.1). The meta-analysis and pooled analysis showed a significant association between oral and pharyngeal cancer and the CYP1A1 MspI homozygous variant (meta-ORm2/m2: 1.9, 95% confidence interval: 1.4-2.7; Pooled ORm2m2: 2.0, 95% confidence interval: 1.3-3.1; ORm1m2 or [infi]m2m2: 1.3, 95% confidence interval: 1.1-1.6). The association was present for the CYP1A1 (exon 7) polymorphism (ORVal/Val: 2.2, 95% confidence interval: 1.1-4.5) in ever smokers. A joint effect was observed for GSTM1 homozygous deletion and the CYP1A1 m1m2 variant on cancer risk. Our findings suggest that tobacco use and genetic factors play a significant role in oral and pharyngeal cancer.