Moreover, several recent studies of anti-PD-1/PD-L1 antibodies in gastric adenocarcinoma have reported a relatively strong relationship between PD-L1 expression and the rate of response to anti-PD-1/PD-L1 immunotherapy [21–23], which makes it important to identify the exact expression condition of PD-L1 in patients with gastric adenocarcinoma. This evidence concerns the gene PDCD1 and gastric adenocarcinoma.