ABSTRACT
Squamous cell cancer has a very high incidence in the coastal areas of the Caspian Sea, in northern Iran, in the Transkei province of South Africa, in the former Soviet republics of Turkmenistan, Kazakhstan and northern Siberia, in Afghanistan, as well as the Henan province in northern China, and along the coast of southern China. Over 200 cases per 100,000 populations has been reported. By contrast, this cancer is relatively uncommon in the United States, Canada, Australia and most areas of Europe with the notable exceptions in certain parts of France and Italy. In low incidence areas, only 3-10 cases per 100,000 population are affected. Such variations, even within close geographic regions, suggest environmental factors as the main etiologic agents.
