ECRG4: Esophageal carcinoma-related gene 4 (ECRG4) is a novel candidate tumor suppressor gene that has frequently been found to be inactivated by promoter hypermethylation in different cancer types, including esophageal cancer, prostate cancer, gastric cancer, colorectal carcinoma, and glioma [78,79,80]. This evidence concerns the gene ECRG4 and prostate carcinoma.