The image to the right shows the inside of a normal large bowel. This mucosa is able to absorb water. The main functions of the bowel are to absorb water and to retain waste products until they are evacuated. Colorectal cancer occurs frequently in developed countries and is the second most common cancer in American men and women. It is estimated that 140,000 new cases are diagnosed each year in the United States, and 60,000 colorectal cancer deaths occur each year.
Colorectal cancer is more common with increasing age.
Incidence rates double each decade from 40 to 80 years. The disease affects men and women equally. Many researchers have tried to identify the cause of colorectal cancer. It is more common in those who eat lots of fat and meatbut little fiber, and is very rare in some countries where the population eats a low meat, high-fiber diet. Other factors associated with the development of colorectal cancer include having an inherited disease such as familial adenomatous polyposis or having a close relative with the disease.