On the other hand, the GSTT1 null genotype in gastric cancer and null genotypes of GSTM1 and GSTT1 in colorectal cancer were not statistically significant.
Colorectal cancer: the risk is greater for carriers of the GSTM1 null genotype (odds ratio [OR] = 1.91, 95% confidence interval [CI] = 1.25-2.91), for carriers of the GSTT1 null genotype (OR = 3.62, 95% CI = 2.34-5.62), and for simultaneous carriers of both GSTM1 and GSTT1 null genotypes (OR = 4.98, 95% CI = 2.77-9.00).
Genetic variation in genes for the xenobiotic-metabolizing enzymes CYP1A1, EPHX1, GSTM1, GSTT1, and GSTP1 and susceptibility to colorectal cancer in Lynch syndrome.
Secondary end points showed that individuals with both the GSTT1 null and NAT2 slow genotypes combined appeared to be at increased risk of colorectal cancer (odds ratio = 2.33; 95% confidence interval, 1.1-5.0).
Of the gene-gene interactions studied, the composite genotype of CYP1A1*2A or CYP1A1*2C and GSTT1 polymorphisms was associated with a decreased risk of colorectal cancer, showing a nearly statistically significant (Pinteraction = 0.06) or significant interaction (Pinteraction = 0.02).
Since GSTM1/GSTT1 genotype and dietary isothiocyanate (ITC) intake had previously been identified as CRC risk factors in this cohort, we now explored if they influenced the CCND1/CRC association.
While the genetic polymorphisms GSTM1 and GSTT1 have drawn particular interest in relation to cancer susceptibility, previous studies of colorectal cancer are inconsistent regarding their role.
Multivariate analysis showed a significant 1.7-fold risk for CRC associated with the GSTT1-null genotypes (p = 0.04) and this increased to 2.9 for smokers (p = 0.02).
We detected a significant high correlation between predisposition for CRC and presence of the Ile/Ile genotype of the GSTP1 (IIe105Val) gene polymorphism, but we did not find a significant relationship between predisposition for CRC and GSTT1 and M1 deletion polymorphisms.
In addition, the frequencies of the GSTM1 and GSTT1 deletion genotypes differed significantly between the cases and controls for current smokers; the GSTT1 null genotype especially is associated with a greater risk of colorectal cancer (OR = 2.44, 95% CI: 1.24-4.81).
Association between exposure-relevant polymorphisms in CYP1B1, EPHX1, NQO1, GSTM1, GSTP1 and GSTT1 and risk of colorectal cancer in a Czech population.
This meta-analysis suggests that the null genotypes of GSTM1 and GSTT1 and the dual null genotype of GSTM1/GSTT1 were all not risk factors in CRC in Chinese population.
For tumor protein 53 (TP53), N-acetyl transferase 1 (NAT1), NAT2, glutathione-S transferase Mu (GSTM1), glutathione-S transferase Theta (GSTT1), and glutathione-S transferase Pi (GSTP1) polymorphisms, the best estimates are sufficient to exclude a 1.7-fold increase in risk of colorectal cancer.
The three-way interaction analysis revealed that interactions between GSTM1 genotype and cigarette smoking and between GSTT1 genotype and alcohol drinking further modified the oxidative stress contribution for colorectal cancer (p for interaction were 0.067 and 0.054, respectively).
We found that men featuring the CYP1A1*2C G/G genotype, the GSTT1 null genotype and XPD 751 with the Gln allele were associated with an elevated risk of colorectal cancer than were men who did not exhibit such genetic features.
Our results suggest that GSTT1 and GSTP1 could play a role in the occurrence of KRAS2 and TP53 mutations in colorectal cancer and generate a hypothesis on the dietary factors that could be incriminated.