By: Indu Ohri for Body1
Virtual colonoscopy, also called computed tomographic (CT) colonography, has emerged recently as a possible alternative to standard optical colonoscopy for colon cancer screening.
Colon cancer is one of the deadliest types of cancer today. It is the third most common cancer in men and women and the third leading cause of cancer-related deaths in the United States. Every year, about 150,000 Americans are diagnosed with colon cancer and 50,000 more die from it.
Fortunately, colon cancer is also one of the most preventable types of cancer because screening tools allow for early medical intervention. Age is the biggest risk factor for developing colon cancer, since over 90 percent of cases are diagnosed in people ages 50 and older. Most medical guidelines recommend that people in this age group receive a colonoscopy every ten years. According to the American Cancer Society, however, only about 40 percent of those over 50 are receiving any type of screening for this condition.
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The American Cancer Society offers the following tips to preventing colon cancer along with beginning regular colon cancer screening at age 50:
Adopt a healthy diet – Limit your intake of red meats (beef, lamb, or liver) and processed meats (hot dogs and some lunch meats), which can increase the risk of colon cancer. A diet rich in fruits and vegetables has been linked with a decreased risk of colon cancer.
Increase your exercise – If you are not physically active, you have a higher chance of developing colon cancer. The American Cancer Society suggests at least 30 minutes, preferably 45 to 60 minutes, of physical activity 5 or more days a week.
Quit smoking – Long-term smokers are more likely than non-smokers to develop and die from colorectal cancer. Talk to your doctor about ways to quit smoking and cope with nicotine withdrawal symptoms.
Limit your alcohol consumption – Avoiding excessive alcohol intake may help lower your risk of colon cancer. The American Cancer Society recommends no more than 1 drink per day for women or 2 drinks per day for men.
Know your family medical history – If you have a family history of developing polyps or colon cancer, you are at an increased risk of developing colon cancer. You should talk with your doctor to see if you should receive colon cancer screening earlier than age 50.
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Medical professionals hope that these alarming statistics will change thanks to virtual colonoscopy. Two recent studies compared the effectiveness of virtual colonoscopy as a screening tool to optical colonoscopy. In the first study, published in the Journal of the American Medical Association (JAMA), doctors from Italy’s Institute for Cancer Research and Treatment found that the virtual colonoscopy correctly identified 155 of 171 (91 percent) people with polyps 6 mm or larger and 667 of 760 (88 percent) people without cancerous lesions.
In a second study conducted by Dr. C. Daniel Johnson, a professor of radiology at Mayo Clinic, virtual colonoscopy detected 90 percent of polyps over 9 mm in diameter. The procedure did not do as well at identifying small polyps, detecting only 78 percent of polyps 6 mm to 9 mm in diameter.
During a virtual colonoscopy, the patient lies down on a table and a soft tube is inserted into the anus to inflate the colon with air or carbon dioxide so it can be viewed more clearly. The patient is then moved into a ring-shaped opening in the center of a CT scanner and X-rays take many cross-sectional pictures of the patient’s body. A computer combines these pictures into 3-D images of the rectum and colon so a doctor can examine those areas for polyps.
In an optical colonoscopy, a long flexible tube with a light and camera on the end enters the anus and passes through the rectum and colon. The doctor examines the colon in real time from a video monitor and removes any polyps that could develop into cancer. Both procedures require a clear liquid diet and bowel prep the night before to cleanse the colon so the doctor can view the inside surface of the rectum and colon.
Virtual colonoscopy has a number of advantages over standard colonoscopy. It is less expensive, anesthesia- and sedation-free, quicker to perform, and less invasive. It also provides a greater view of the body outside of the colon, which allows for the discovery of other serious medical problems. In Johnson’s study, 16 percent of patients were found to need more testing or immediate care for problems besides colon cancer with virtual colonoscopy.
The procedure does have a number of drawbacks not present in optical colonoscopy. The most important shortcoming is that virtual colonoscopy can perceive polyps, but a separate optical colonoscopy is required to remove them. As a screening tool, it also cannot detect small polyps or flat polyps that lay along the colon wall with the same precision as an optical colonoscopy. Low-income patients and the elderly may find it difficult to access virtual colonoscopy because Medicare and Medicaid have chosen not to pay for it as a screening tool for colon cancer.
Doctors warn that virtual colonoscopy may not be for everyone. In particular, they advise that only people who have a lower risk for colon cancer should use it as a screening tool. High-risk individuals include those with a family history of colon cancer, a personal history of polyps removed from the colon, or a positive fecal occult blood test (FOBT). Despite these limitations, the doctors involved in the study at the Institute for Cancer Research and Treatment hope that this noninvasive procedure will convince those who are hesitant about optical colonoscopy to be screened for colon cancer and receive early preventative care.
