PDCD1 and pancreatic neoplasm: Twenty‐six studies [10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 34, 35, 36] which assessed the association between immune cell markers (CD3, CD4, CD8, CD15, CD20, CD68, CD163, CD204, CD206, FoxP3, programmed cell death 1 [PD‐1], programmed cell death ligand 1 [PD‐L1] and folate receptor β macrophages), identified by IHC in pancreatic tumour tissue, and survival were eligible for qualitative review.