ABSTRACT
Colorectal cancer is the fourth commonest form of cancer which occurs worldwide, with an estimated 782 900 new cases diagnosed in 1990.1 Global, agestandardized rates of colorectal cancer (ICD9 153 and 154) incidence are slightly higher in men than in women (19.4 and 15.3 per 100 000 respectively).1 The disease is most frequent in occidental countries, and particularly so in North America, Australia, New Zealand, and parts of Europe. The incidence of this malignancy shows considerable variation among racially or ethnically defined populations in multiracial/ethnic countries. The diseases of colon and rectal cancer appear to be distinct, but, unfortunately, there are recognized difficulties in distinguishing colon and rectal cancer in mortality statistics for a variety of reasons.2 Wherever possible in this chapter, the distinction between colon and rectum will be preserved.
