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

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. 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). 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