Previous studies reported that the PDCD-1.5 (rs2227981) polymorphism was an asynonymous mutation (C to T, Ala to Ala)[2,24]; it may influence the expression and function of PDCD1 through linkage disequilibrium with other nucleotide polymorphisms in PDCD1 gene or other nearby genes.[2,24] Accordingly, the polymorphism may influence the susceptibility to cancer through these mechanisms. Here, PDCD1 is linked to cancer.