PDCD1 and cancer: Diverse search terms were used, including, but not limited to “tumour-infiltrating lymphocytes”, “TILs”, “T cells”, “T lymphocytes”, “CD3 T cells, “CD8 T cells”, “CD4 T cells”, “FoxP3 T cells”, “regulatory T cells”, “B cells”, “PD-1”, “Programmed Cell-death 1”, “CD103”, “CD39”, “TIGIT”, “TIM-3”, “LAG-3”, “CTLA-4” “Prognosis”, “Survival”, “Cancer”, “Outcome”, “Tertiary Lymphoid Structures”, “Machine-learning”, “Deep-learning”, “Immunohistochemistry”, “Immunotherapy”, “Checkpoint Inhibition”, “Prediction”, “Predictive Value”, “Biomarker”.