BACKGROUND: Glutathione transferases (GST) detoxify environmental and endogenous 
compounds and levels of two polymorphic GST proteins, GSTM3 and GSTP1, are high 
in the brain. Previous studies of GSTM3 and GSTP1 polymorphisms and adult brain 
tumor risk have produced inconsistent results, whereas the GSTM3 -63 variant is 
newly identified and, therefore, has not yet been studied in this context. We 
therefore examined associations between GSTM3 -63, GSTM3 *A/*B, GSTP1 105, and 
GSTP1 114 variants and adult brain tumor risk and the interaction of the effects 
of these same polymorphisms with cigarette smoking. In addition, the enzymes 
NQO1 and CYP1A1 alter susceptibility to oxidative brain damage. Because there is 
less previous evidence for a role of NQO1, CYP1A1, GSTM1, and GSTT1 variants, we 
restricted analysis of these variants to a small preliminary study.
METHODS: We genotyped DNA collected for an international population-based 
case-control study of 725 glioma cases, 329 of which were glioblastoma cases, 
546 meningioma cases and 1,612 controls. Study participants were residents of 
Sweden, southeast England, Denmark, and Finland.
RESULTS: We found no associations between the GSTM3, GSTP1, NQO1, CYP1A1, GSTM1, 
or GSTT1 polymorphisms and adult brain tumor risk with the possible exception of 
a weak association between the G-C (Val-Ala) GSTP1 105/114 haplotype and glioma 
[odds ratio (OR), 0.73; 95% confidence interval (95% CI), 0.54, 0.99], nor was 
there an interaction between the effects of the GSTM3 or GSTP1 polymorphisms and 
cigarette smoking.
CONCLUSIONS: Overall, we observed no strong evidence for an association between 
GST or related enzyme polymorphisms and adult brain tumor risk.