Esophageal Carcinogenesis

Esophageal cancer is the sixth leading cause of cancer death and remains one of the least survivable cancers. Esophageal cancers show wide variations in incidence in different population, suggesting that environmental or lifestyle risk factors could be controlled to reduce risk of these diseases. There are two major histopathologic types (squamous cell carcinoma and adenocarcinoma) of esophageal epithelial malignancy. Recently, the rate of adenocarcinoma is increasing in developed countries: in the United States, 50% or more is adenocarcinoma and, in about 70%, the increase especially in a white male serves as adenocarcinoma. Esophageal adenocarcinoma develops in the lower esophagus. In contrast, in Japan, the increase in adenocarcinoma is not clear and most (90%) of esophageal cancers are squamous cell carcinoma. Such squamous cell carcinoma occurs onto the middle part esophagus mostly, and 60% or more of the whole esophagus cancer also develops in the middle and upper parts. These differences also influence the treatment results. The scope of this article is to discuss carcinogenesis in the esophagus by giving an overview about its histopathological characteristics and molecular mechanisms.