ACE2 is downregulated in hepatocellular carcinoma (59), non-small cell lung cancer (NSCLC) (60), breast tumors (61), pancreatic ductal adenocarcinoma (62), and gallbladder cancer (63); ACE2 and TMPRSS2 are both upregulated in colorectal tumor (64) and lung cancer (65). TMPRSS2 is downregulated in head and neck cancer (66). This evidence concerns the gene TMPRSS2 and head and neck cancer.