But there's new evidence that the most widely used screening exam is not getting the job done reports CBS News Medical Correspondent Dr. Emily Senay
According to a study in Thursday's New England Journal Of Medicine among two different types of colon cancer screening tests that use a scope to look inside the colon, the one that looks the furthest is the one that catches the most cases of colon cancer.
The new study found that sigmoidoscopy only looks at the lower part of the colon, whereas a colonoscopy goes the distance and looks at the entire colon.
Both tests use a flexible rod with a light and a camera on the end that allows doctors to see the colon wall and check for signs of cancer.
In the study researchers looked at 3,000 men who had no symptoms of colon problems. But 10 percent were found to have cancer or early signs of cancer when screened with the full colonoscopy.
During the screening, doctors look for polyps that are cancerous and remove them. "If you remove them, you reduce the risk of developing cancer. It's inside the polyps that the cancer develops, " said Dr. Senay.
But Dr. Senay said it doesn't mean that you shouldn't have a sigmoidoscopy. "In some cases it might be appropriate. For most people who have a family history, they say the colonoscopy is the way to go.
Dr. Senay said the frequency of having a colonscopy would be based on your family history, which plays a very strong role with your decision to screen. "If you were totally clean and there's no family history, probably five years. There may be research which shows that even ten years may be safe."
"If you have someone, a relative, who's had colon cancer, you need to start screening ten years before the age at which that person developed colon cancer."
Researchers estimate that using colonoscopy could decrease cases of colon cancer by 75 percent per year, an enormous improvement.
But the problem with that is only 30 percent of Americans get any screening at all. The current recommendations are for regular testing of stool samples at age 50, along with a test called a sigmoidoscopy every five years.
In most cases colonoscopies aren't covered by health insurance. However, Dr. Senay said "with these new studies, that may change."
"To make a major change in recommendation for screening would have to come from the government. There's a lot left to be done before this is widely recommended," added Dr. Senay.
Colon cancer is curable if caught early enough.
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