A colonoscopy is an exam in which  a flexible tube with a fiber optic light and camera (colonoscope) is passed through the rectum along the full length of the colon (large intestine). It is done to screen for colon cancer and to diagnose diseases of the bowel such as colitis, irritable bowel syndrome and diverticulosis.
Colorectal cancer (colon cancer) develops in the colon or rectum. Before a cancer develops, there are often changes in the lining of the intestines. One of these changes is the abnormal of tissue, called a polyp (link). Although usually benign (non cancerous), a polyp may develop into colon cancer. They vary in size from tiny to several millimeters in size and usually are removed during a colonoscopy
Beginning at age 50, individuals at average risk for colon cancer should have one of these five screening option, according to the American Cancer Society:
  • A fecal occult blood test (FOBT)  or fecal immunochemical test (FIT) every year**
  • Flexible sigmoidoscopy every 5 years**
  • An FOBT* or FIT* every year plus flexible sigmoidoscopy every 5 years (of these first 3 options, the combination of FOBT or FIT every year plus flexible sigmoidoscopy every 5 years is preferable.)
  • double-contrast barium enema every 5 years**For FOBT or FIT, the take-home multiple sample method should be used.
  • colonoscopy every 10 years (colonoscopy should be done if the FOBT or FIT shows blood in the stool, if sigmoidoscopy results show a polyp, or if double-contrast barium enema studies show anything abnormal. If possible, polyps should be removed during the colonoscopy.)
Many individuals are at heightened risk for colon cancer. The key factors that can increase risk are: 
  • Age: Simply being over the age of 50 is the most common risk factor for developing colon cancer.
  • A personal history of colon cancer: People who have had colon cancer are more likely to have a recurrence.
  • A personal history of polyps:  While most polyps are benign, some may develop into colon cancer.
  • A personal history of inflammatory bowel disease: Conditions such as ulcerative colitis and Crohn’s disease increase the risk of colon cancer.
  • A family history of colon cancer or polyps.
  • Familial adenomatous polyposis (FAP) – a hereditary condition which results in the development of hundreds of polyps in the colon and rectum. Cancer may occur between the ages of 30 and 50 in patients with this condition.
  • A diet high in animal fats from animal sources can increase the risk of colon cancer.
  • Physical Inactivity: Inactive individuals are more likely to develop colorectal cancer.
  • Obesity: Being very overweight increases the risk of dying from colorectal cancer.
  • Smoking: Smokers are 30 to 40 percent more likely than non-smokers to die from colorectal cancer.
  • Alcohol use: Colorectal cancer has been linked to the heavy use of alcohol. What is colon cancer? What is a polyp?
Individuals with one or more risk factor should consult with their doctors about the appropriate tests and frequency of tests.
For more information regarding this procedure, click here.