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Cancer shows both geographic and temporal variability.
There are different patterns of cancer at different places and
different times. These patterns relate both to habits and to
environmental hazards.
Habits:
The use of tobacco has resulted in lung cancer in North America and
Europe during the last half of the 20th century.
Dietary habits underlie the high incidence of stomach cancer in
Japan, Northern China, Chile and Eastern Europe. This tumor is
associated with lower socioeconomic status. The incidence falls
in second generation Japanese who have moved to the United
States of America.
Food preservation methods are associated with stomach and liver
cancers in West Africa and Southeast Asia. Techniques for
pickling as well as contamination with aflatoxins from mould
are responsible.
Environmental hazards:
Viruses: Hepatitis B Virus is associated with liver cancer.
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