ABSTRACT
This chapter deals with the occurrence of colorectal cancer in human populations. Colorectal cancer represents a major public health problem which has attracted attention both from cancer epidemiology and experimental cancer research. Large bowel cancer is the common denominator for cancer of the colon and rectum, which by the World Health Organization Disease Classification are regarded as two separate entities, ICD-153 and ICD-154. The different sex ratio for cancer of the colon and cancer of the rectum clearly suggest that etiological factors for malignant neoplasms of these two parts of the large bowel may at least in part be different or carry different weights. Geographical variations in incidence of large bowel cancer are known to exist within countries where mortality or incidence has been recorded and described for small areas. Cancer of the large bowel is primarily a disease of the industrially developed parts of the world.
