70 THE CHINA STUDYwell understood. It was to be a monumental survey of death rates for
twelve different kinds of cancer for more than 2,400 Chinese counties
and 880 million (96%) of their citizens. The survey was remarkable in
many ways. It involved 650,000 workers, the most ambitious biomedi-
cal research project ever undertaken. The end result of the survey was a
beautiful, color-coded atlas showing where certain types of cancer were
high and where they were almost nonexistent.^1
CHART 4.1: SAMPLE CANCER ATLAS IN CHINACOLON AND RECTUM (FEMAlE)-.-- I
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This atlas made it clear that in China cancer was geographically lo-
calized. Some cancers were much more common in some places than
in others. Earlier studies had set the stage for this idea, showing that
cancer incidence also varies widely between different countries.^2 -4 But
these China data were more remarkable because the geographic varia-
tions in cancer rates were much greater (Chart 4.2). They also occurred
in a country where 87% of the population is the same ethnic group, the
Han people.