The heatmap showed that most of the key genes had median expression levels in tumor tissue, whereas CD74 Molecule (CD74), major histocompatibility complex, class I, E (HLA-E), major histocompatibility complex, class II, DR Alpha (HLA-DRA), major histocompatibility complex, class II, DR Beta 1 (HLA-DRB1), complement C1q B chain (C1QB), complement C1q A chain (C1QA), and complement C1q C chain (C1QC) exhibited the higher expression in samples from cancer patients. This evidence concerns the gene CD74 and cancer.