DRD5 and esophageal squamous cell carcinoma: In 12 tumor types including bladder cancer, breast cancer, esophageal squamous cell carcinoma, and head and neck cancer, hypermethylation in the DRD5 promoter region leads to gene expression silencing, whereas in non-small cell lung cancer, DRD5 expression was elevated in response to docetaxel (59, 60).