Colon cancer screening guidelines released

By Dr. Ananya Mandal, MDMar 7 2012

According to a new guidance statement from the American College of Physicians all adults should get screened for colon cancer once they get older to reduce their risk of dying from the nation's number two cancer killer.

“Only about 60 percent of American adults aged 50 and older get screened, even though the effectiveness of colorectal cancer screening in reducing deaths is supported by the available evidence,” Dr. Virginia L. Hood, president of American College of Physicians, said in a written statement.

A colonoscopy is considered the "gold standard" of screening tools, according to the College. During the 30-minute procedure, a thin, flexible tube with a tiny camera is guided through the large intestine to look for precancerous growths called polyps so they can be removed before they turn into cancer. “If polyps are identified, they are usually removed at the time of the procedure so they do not get a chance to grow into cancer, thereby preventing colon cancer,” said Dr. Bincy Abraham, assistant professor of medicine – gastroenterology at BCM. “Depending on the size, number and type of polyp(s), a repeat colonoscopy is recommended to monitor for any new growths that can occur.” If no polyps are found, the next colonoscopy screening can be done in 10 years for normal risk groups. If polyps are found, follow-up usually ranges from three to five years, however some may need more frequent screening, she said.

There are alternative screening options available including

• Barium enema: special X-rays of the colon and rectum.
• Virtual colonoscopy: a CT scan image of the colon that does not require the use of an endoscope.
• Flexible sigmoidoscopy: using a lighted scope, the procedure allows a physician to see inside the sigmoid colon and rectum

Abraham said having a traditional colonoscopy is ideal because it allows the physician to view the entire colon and it is both diagnostic and therapeutic. For example, a barium enema or a virtual colonoscopy could miss small polyps. “If polyps are found, the patient would still have to undergo preparation and schedule for a colonoscopy to remove them.” A flexible sigmoidoscopy only looks at a small portion of the colon and it could miss polyps or cancers in the right side of the colon.

The College’s new guidance statement includes recommendations from guidelines developed by other medical societies. According to the ACP, most adults should get screened for colon cancer beginning at age 50. People with a family history of colon cancer and others considered high-risk should get screened starting at age 40, or 10 years younger than the age of when your youngest family member was diagnosed with colon cancer. Other risk factors for colon cancer include age, race - African Americans have highest rates in U.S. - history of polyps or inflammatory bowel disease.

For those who want other options, there is a stool blood test the College recommends people get annually, or a flexible sigmoidoscopy - a thin camera tube that's inserted that looks at the lower parts of the colon - that people should get every five years.

“We encourage patients to engage in shared decision making with their physician when selecting a colorectal cancer screening test so that they understand the benefits and harms,” Hood said in the statement. “The success of any screening program, especially colorectal cancer screening, is dependent on the appropriate testing and follow-up of patients with abnormal screening results as well as following up with patients for repeat testing at designated intervals.”

The ACP further says that it does not recommend continued screening for adults over 75 because the harms - such as the need for biopsies if something is found - would outweigh the benefits at that age because the cancers may be too slow-growing to ever cause a problem. The College's position statement is available online in the March 6 issue of Annals of Internal Medicine.

Colon cancer is largely preventable as long as a person gets screened appropriately, said a gastroenterologist from the NCI-designated Dan L. Duncan Cancer Center at Baylor College of Medicine. Despite new options for screening, there is plenty of evidence to support that a traditional colonoscopy is still the best method of prevention, said Dr. Bincy Abraham.

Colon cancer is expected to take more than 51,000 American lives this year, second to only lung cancer. A recent study says the procedure actually saves lives. It found people who got a colonoscopy were 53 less likely to die from colon cancer than people who weren't screened. “There's no question that these are findings that we can take to the bank,” Robert Smith, director of screening at the American Cancer Society, said at the time. March is National Colon Cancer Awareness Month. It serves as an opportune time for everyone to be reminded and educated on the importance of colon cancer screening, Abraham said.