Based on subgroup analysis by type of cancer, the PD-1.6 polymorphism remarkably elevated the risk of AML (G vs. A: OR = 1.34, 95% CI = 1.06-1.71, P = 0.017; GA vs. AA: OR = 1.49, 95% CI = 1.06-2.09, P = 0.020; GG+GA vs. AA: OR = 1.52, 95% CI = 1.10-2.09, P = 0.011, Supplementary Table 3). This evidence concerns the gene PDCD1 and acute myeloid leukemia.