POLR1D and cancer: Using bioinformatics tools, we analyzed and identified the cancer stem cell marker genes (CSCMGs) of OSCC and further constructed and validated a six-gene prognostic signature (6-GPS, consisting of Adrenomedullin (ADM), RNA polymerase 1 subunit D (POLR1D), Prostaglandin reductase 1 (PTGR1), L35a ribosomal protein (RPL35A), Phosphoglycerate kinase 1 (PGK1) and Prolyl 4-hydroxylase subunit alpha 1 (P4HA1)) for OSCC.