PDCD1 and cancer: Therefore, we conducted this meta-analysis to validate the relationships of PD-1.5 (rs2227981), PD-1.9 (rs2227982), PD-1.3 (rs11568821), PD-1.1 (rs36084323), PD-1 rs7421861, PD-L1 rs4143815, PD-1.6 (rs10204525), PD-L1 rs2890658, rs10815225, rs17718883, and rs2297136 gene polymorphisms with risk of cancer.