The incidence of cancer at various body sites may differ in different countries. Oral cancer is common in India as a consequence of chewing tobacco. Stomach cancer is more frequent in China and Japan, as well as in South and Central America (Mexico, Costa Rica) and also Eastern Europe. Primary cancer of the liver is uncommon except in portions of Africa, east Asia and the western Pacific. Cervical cancer is more common in developing countries especially in situations of low socioeconomic status. Epidemic levels of cigarette smoking have led to the high incidence of lung cancer in developed countries, for example, North America, Europe and Shanghai in China, but it is low in Africa.
 

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