The association between polymorphisms in the PDCD1 gene and the risk of cancer: A PRISMA-compliant meta-analysis

BACKGROUND: The effects of the programed cell death 1 (PDCD1) gene polymorphisms on cancer risk have been investigated in some studies; however, the results were conflicting and ambiguous. Therefore, we aimed to do a meta-analysis to investigate the association of PDCD1 polymorphisms with cancer risk from all eligible case–control studies. MATERIALS AND METHODS: An electronic search of the PubMed, Embase, Chinese National Knowledge Infrastructure, and Wanfang databases was performed. The association between PDCD1 polymorphisms with cancer risk was calculated with odds ratios (ORs) and their corresponding 95% of confidence intervals (CIs). RESULTS: A total of 24 case–control studies from 13 articles that investigated the associations of 5 widely studied polymorphisms in PDCD1 gene and cancer risks were included. The results of meta-analysis: the PDCD-1.5 (rs2227981) and PDCD-1.3 (rs11568821) polymorphisms were associated with decreased risk of cancer (rs2227981: OR = 0.75, 95% CI: 0.64–0.86, P < 0.0001 for TT vs TC + CC; rs11568821: OR = 0.79, 95% CI: 0.65–0.96, P = 0.02 for TC vs TT), while no significant associations were found for the other 3 polymorphisms (PDCD-1.9 [rs2227982] polymorphism: OR = 1.03, 95% CI: 0.90–1.18, P = 0.66 for CC + TC vs TT; PDCD1 rs7421861 polymorphism: OR = 1.10, 95% CI: 0.96–1.25, P = 0.16 for CC + TC vs TT; PDCD-1.6 [rs10204525] polymorphism: OR = 0.93, 95% CI: 0.82–1.05, P = 0.24 for GG + GA vs AA). CONCLUSION: The meta-analysis suggests that the PDCD-1.5 (rs2227981) and PDCD-1.3 (rs11568821) polymorphisms are associated with susceptibility of cancer. Further studies with larger sample sizes are required to make a better assessment of the above association.