Key to colon cancer prevention is regular screenings

Oct 4 2007

More than 100,000 people will develop colon cancer in 2007, according to the American Cancer Society; the disease currently causes more than 55,000 U.S. deaths annually.

However, the incidence of colon cancer-related mortalities has decreased in recent years, partly due to increased screening for the disease and the removal of colon polyps, the tumors that form inside the large intestine, detected during screening, according to UCLA's Healthy Years.

Ninety percent of people with colon cancer are over age 50, so it's best for all older adults to be screened for the disease regularly. “Presently, one of the most effective and potentially life-saving methods of prevention for colon cancer is the use of screening colonoscopies,” says Eric Esrailian, MD, MPH, section head for General Gastroenterology and the Digestive Diseases Center at UCLA Medical Center. “Colonoscopies can not only detect and enable the removal of polyps before potential transformation to cancers, but the procedure can also allow for the early detection of cancer at a potentially curable stage.”

Physicians recommend that people age 50 and older have a colonoscopy every three to 10 years, depending on their personal risk factors. For example, someone with a family history of colon cancer is at an increased risk for the disease and should be tested every three to five years. Another known risk factor for colon cancer is a diagnosis of inflammatory bowel disease. Talk to your doctor about your potential risk factors—others include obesity, cigarette smoking, and heavy alcohol consumption—and how often you should have a colonoscopy.

Colon cancer screening. Unfortunately, current screening techniques for colon cancer are not quite as simple as a blood test or urinalysis. While a fecal exam can be done to test for blood in the stool, polyps do not always cause bleeding so additional testing is required. A study published in Cancer Research in June revealed that scientists have identified colon cancer-specific antigens that show promise as potential markers for detecting the disease. These antigens are found in the blood, so it may one day be possible to test for colon cancer using a blood sample. In the meantime, doctors rely mainly on the colonoscopy to identify cancer and potentially cancerous polyps.

Currently, two kinds of tests screen for colon cancer: the colonoscopy and the “virtual” colonoscopy, also known as a computed tomographic (CT) colonography. The CT colonography is less invasive than the traditional colonoscopy, but both tests require bowel preparation. “There is ongoing research into finding the best-tolerated and most effective preparation to cleanse the colon prior to the procedure, but it will always be the most difficult part of the colonoscopy experience,” says Kirsten Tillisch, MD, a gastroenterologist at UCLA Medical Center. “In the future, it may be possible to do a ‘virtual' colonoscopy without bowel preparation, but that is not currently an option.”

Both the colonoscopy and CT colonography require that the contents of your colon be emptied prior to the procedure. Preparation usually requires you to stop eating solid foods a day or two before the exam and take laxatives so that the colon is empty and it is easier to see polyps.

The actual colonoscopy exam requires sedation, so you will have to get someone else to drive you home from the hospital following the procedure. After you are sedated, the doctor will insert a long tube with a camera on the end into your colon. During the colonoscopy, the doctor can remove any polyps that are detected, as well as take samples for biopsy.

A CT colonography is less invasive than the traditional colonoscopy and therefore does not require sedation. This type of test uses X-ray technology to view the colon. There has been some debate among researchers as to whether or not the CT colonography is as accurate as the traditional colonoscopy. The CT colonography also does not allow for polyp removal; therefore, if polyps are detected, a colonoscopy must be performed anyway. “For now, traditional colonoscopy is the best option for most people and is very well tolerated,” Dr. Tillisch says.

Prevention: What's on the horizon? “Right now, the notion of prevention for colon cancer is an important topic for patients, clinicians, and researchers. As the second most-common cancer in our society, all aspects of the prevention, diagnosis, and treatment warrant frequent evaluation and re-evaluation,” says Dr. Esrailian.

Recent findings suggest that some compounds found in processed and red meat might contribute to colon cancer; that coffee consumption might help prevent colon cancer; and that aspirin use might also lower colon cancer risk. Other foods being studied for their potential preventive abilities include green tea, fish, and blueberries. However, experts advise that such data should not be viewed as definitive evidence without corroboration with other studies. Patients should always discuss information they glean from published reports with their doctors to determine its significance with respect to their own situations.

The real key to colon cancer prevention is regular screenings. Even though the experience of having a colonoscopy may be inconvenient or unpleasant, it could end up saving your life. “The good thing is that most people only need to have a colonoscopy every three to 10 years, depending on their personal risk factors, so two days out of that time is not too bad, especially if you are preventing cancer,” says Dr Tillisch.