Fig. 1 Cross sectional view of a polyp in the colon. Fig. 2 3-Dimensional "virtual colonography" view of 2 polyps.

Colorectal cancer kills more Americans than any other malignancy except lung cancer. In 2003, 148,000 new cases of colorectal cancer will be diagnosed and 56,000 will die from advanced disease.

It is possible to prevent colorectal cancer by finding and removing adenomatous polyps, the precursors of most colorectal cancers. At present, the best test for identifying polyps and cancers is colonoscopy. Colonoscopy remains the gold standard for colon cancer screening, and allows for both detection and removal of polyps during the same procedure. However, only approximately one-half of the people in the United States who should undergo colonoscopy actually do, leaving a large portion of the population at risk for undiagnosed polyps and potentially at risk for developing colon cancer.

Like colonoscopy, virtual colonography is performed following a 24 hour bowel cleansing. Using the latest CT technology coupled with 3-D image rocessing, virtual colonography can be used to detect polyps 1 cm or larger with more than 90% accuracy. Virtual colonography offers a minimally invasive alternative for patients who are unable or unwilling to undergo a colonoscopy.

Why screen for colon cancer?

By the time most colorectal cancers cause abdominal symptoms or obvious rectal bleeding, they may have already spread beyond the bowel limiting the chance of a surgical cure. However, when these slowly-developing cancers are diagnosed by screening before any symptoms occur, most are still confined to the bowel and the chance of a surgical cure is 80-90%.

What are the advantages of virtual colonography?

• Virtual colonography is less invasive than colonoscopy.
• Virtual colonography requires no sedation. Patients may return to work or other activities following the examination.
• Virtual colonography provides images of the abdominal organs as well as the colon. These images are similar to those obtained during Be Well's abdominal scan, and provides screening for abdominal aortic aneurysms and many forms of cancer.
• Virtual colonography can be used to detect polyps 1 cm or larger with more than 90% accuracy.

What are the disadvantages of virtual colonography?

• Colonoscopy will reliably detect polyps at a smaller stage than virtual colonography.
• If a polyp is detected during virtual colonography, you will then need to undergo a colonoscopy to have the polyp removed.

Who should undergo screening for colon cancer?

• Current guidelines recommend colon cancer screening for all people over the age of 50.
• Patients with the following are considered to be at higher risk than the general population for developing colon cancer:
  • Mother, father, sister or brother has had colon cancer
  • Personal history of ovarian, endometrial or breast cancer

Are there any people in whom virtual colonography is not recommended or appropriate?

• Virtual colonography should not be performed in patients with known or suspected inflammatory bowel disease.
• Patients with previously diagnosed colon cancer, or who have previously undergone colonoscopy and have had a polyp removed should follow-up with their primary care physician, gastroenterologist or surgeon rather than undergoing a virtual colonography.

It is important to note that conventional colonoscopy is still considered to be the "gold standard" for colon cancer screening. If an abnormality is found on virtual colonography, conventional colonoscopy or surgery will be necessary to remove the polyp or cancer.

How is the Virtual CT Colonoscopy Performed?

The Day Prior to Your Scheduled Exam:

Patients commence bowel preparation 24 hours before the virtual colonography. Be Well Body Scan will mail you the bowel cleansing preparation before your scheduled exam.

The Day of Your Exam:

With virtual colonoscopy, air is introduced into the colon through a small, soft-tipped rectal tube. A helical CT scan is performed through the colon first with the patient lying face up, and then again lying face down. The CT images are assembled on a computer work station, creating both a 2- and 3-dimensional model that is examined by the radiologist for polyps and other abnormalities.

• The entire examination takes approximately 20 minutes
• Because there is no sedation involved, patients can leave Be Well and return to normal daily activities
• Following the examination, the radiologist will review your images on a 3-D work station. He/she will contact you within 24 hours to discuss your results.

Where can I obtain more information on colon cancer screening?

Additional information about colon cancer screening can be found at:

• http://www.cdc.gov/cancer/screenforlife/index.htm
• http://www.ccalliance.org
• Article, "Researchers Boost 'Virtual' Colonoscopy", Boston Globe, December 2, 2003