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Colon Cancer

The colon and the rectum are the final sections of the large intestine. In the United States, approximately 150,000 people are diagnosed with colorectal cancer every year and of these, approximately 55,000 will die of the disease. Cancer of the colon is the second leading cause of cancer death in the United States. Most experts agree that it is preventable.


Virtual Colonoscopy shows obstructing cancer in the sigmoid colon (yellow arrows). The endoscope was unable to pass through this cancer and hence the beginning of the colon could not be seen at endoscopy


Virtual Colonoscopy however was able to see the beginning of the colon in this patient and found additional small polyps.

Risk factors for the development of colorectal cancer include a low fiber diet, a family history of colorectal cancer, inflammatory bowel disease, multiple polyps (small lesions along the membrane of the colon or rectum--these can be hereditary or non-hereditary) and a previous history of colorectal cancer or adenomatous polyps (growths that develop on the membrane of the large intestine). But, the majority of all colorectal cancers arise in patients without any known risk factor. The incidence of the disease increases with age.

Colorectal cancer develops from polyps, which if removed early in their growth, will never progress to invasive cancer. This fact is the basis of the wide acceptance of screening for colorectal cancer by the medical community. The American Cancer Society, the Centers for Disease Control, the American College of Gastroenterology, the American College of Surgeons, and the American College of Radiology all advocate screening for colorectal carcinoma (cancer).

Current options available to screen for colorectal carcinoma include a digital (finger) rectal examination, fecal occult blood testing (testing for microscopic amounts of blood in the feces), sigmoidoscopy (examination of the last part of the colon with a tubular instrument), barium enema, and fiberoptic colonoscopy (examination of the entire colon with the use of fiber optics). Virtual colonoscopy is a new screening test in which a skilled radiologist uses a CAT (Computer Assisted Tomography) scanner and sophisticated image processing computers to actually recreate and evaluate the inner surface of the colon. The CAT scanner provides the x-ray images; the image processing computers create the 3-D display for the final interpretation. The study gives a complete evaluation of the entire surface of the colon and can be performed quickly.

The following websites also contain helpful information on colorectal cancer: The National Center for Chronic Disease Prevention and Health Promotion, part of the Centers for Disease Control, provides detailed information about colorectal cancer and the value of screening.

The American College of Gastroenterology has a fact sheet on colon cancer, along with information on prevention, screening, and resources.