Additionally, female smokers were shown to have a higher risk of bladder cancer when their blood samples had the GSTM1 deletion genotype, but not in non-smokers (Karagas et al., 2005), possibly due to females with the GSTM1 null genotype being unable to metabolize carcinogens in cigarette smoke. This evidence concerns the gene GSTM1 and urinary bladder carcinoma.