Basma et al. 2013 studied polymorphisms in genes encoding drug-metabolizing enzymes (DMEs) such as Cytochrome P450 2E1 (CYP2E1), NAD(P)H quinone oxidoreductase1 (NQO1), and N-Acetyltransferase1 (NAT1) and their influence on bladder cancer risk among Lebanese men. 50 unrelated men, below the age of 50 years with histologically confirmed bladder cancer, and 106 controls were included in the study. Significant clustering of CYP2E1 c1/c1 and NAT1*14A were seen in bladder cancer patients compared to controls. NAT1*14A allele, smoking, and occupational exposure to combustion fumes were observed to significantly contribute to the risk of developing bladder cancer. Although not statistically significant, CY2E1 c1/c1 genotype and prostate related symptoms were also found to be risk factors for bladder cancer.

Darazy et al. 2011 studied the correlation between CYP1A1, CYP2E1, and GSTM1 gene polymorphisms and gastrointestinal cancer incidence among Lebanese subjects. Genotyping for CYP1A1*2A allele, CYP2E1*6 allele, and GSTM1 gene deletion was carried out in 70 patients with histologically confirmed colorectal cancer or gastric cancer, and 70 age and sex matched healthy controls. Significantly higher percentage of patients were homozygous for the GSTM1 deletion polymorphism (GSTM1*0/*0) indicating an association with increased risk of colorectal cancer, gastric cancer, and in general gastrointestinal cancer. Study also indicated a 36.5-fold increase in the risk of gastric cancer among patients with both CYP1A1*2A/*2A and GSTM1*0/*0 genotypes. No significant difference was observed in the distribution of CYP2E1 genotypes among patients or controls.