A preliminary study on ras protein expression in human esophageal cancer and precancerous lesions

INTRODUCTION The esophageal carcinoma is a common malignant tumor in Linzhou City (Linxian) of Henan Province in northern China. Although the etiology and natural history of esophageal carcinoma are not clear, a substantial amount of evidence has been provided to suggest that the development of human esophageal squamous cell carcinomas (SCC) is a multistage progressive process1-4] An early indicator of abnormality in persons predisposed to esophageal SCC is an increased proliferation of esophageal epithelial cells,morphologically manifested as basal cell hyperplasia (BCH), and dysplasia (DYS), and carcinoma in situ, which could be considered precancerous lesions of esophageal SCC1-4].