PDCD1 and cancer: By integrating quantitatively allele or genotype distribution of 5528 patients and 6875 controls, we did not discover any significant relationship between the PD-1.6 SNP and cancer risk in five genetic comparisons (G vs. A: OR = 0.98, 95% CI = 0.86-1.11, P = 0.761; GG vs. AA: OR = 0.98, 95% CI = 0.73-1.32, P = 0.904; GA vs. AA: OR = 1.02, 95% CI = 0.88-1.18, P = 0.861; GG+GA vs. AA: OR = 1.01, 95% CI = 0.86-1.19, P = 0.898; GG vs. GA+AA: OR = 0.96, 95% CI = 0.79-1.17, P = 0.673, Figure 8 and Table 2).