There was no bias for the association of the dual-null GSTM1-GSTT1 genotype with bladder cancer risk, but there was for the GSTM1- and GSTT1-null genotypes (GSTM1-null: Begg P = 0.100, Egger P = 0.052; GSTT1-null: Begg P = 0.001, Egger P = 0.002; dual-null GSTM1–GSTT1: Begg P = 0.343, Egger P = 0.236; Fig. 5). Here, GSTM1 is linked to urinary bladder carcinoma.