HTR6 and head and neck squamous cell carcinoma: As a result, HTR6 expression was positively correlated with the OS of esophageal adenocarcinoma (n = 80), head and neck squamous cell carcinoma (n = 500), hepatocellular carcinoma (n = 371), and ductal adenocarcinoma of the prostate (n = 177), and negatively correlated with lung cancer (n = 1925) and endometrial carcinoma (n = 543) (Figure 2B).