RASSF1 and esophageal squamous cell carcinoma: Accumulated evidences have indicated the possible crucial role of RASSF1A methylation on esophageal carcinogenesis in Chinese population, the methylation rates varied from 14.9% [9] in Beijing with a low incidence for ESCC, to 48.5% [10] in Hangzhou with a higher incidence for ESCC, indicating the disparity of RASSF1A methylation with different environment background.