Two Tests Added to Recommended List to Prevent or Detect Colorectal Cancer

By DENISE GRADY
The American Cancer Society and other health groups are recommending two tests they had not previously endorsed to prevent or detect colorectal cancer, the groups said Wednesday.
The new policy is based on evidence that the tests work well enough to recommend and applies to all adults 50 and older and to some younger people with symptoms or risk factors for colon cancer.
One test is virtual colonoscopy, which uses a CT scan to look for abnormal growths and, unlike the standard colonoscopy, does not require inserting a camera-tipped tube rectally.
The other test examines stool to find abnormal DNA associated with cancer and requires an entire bowel movement be packed in a kit and sent to a laboratory.
The tests are now part of a list of seven testing options from which people can choose. The medical groups are providing as many options as possible, they say, hoping patients find one acceptable.
Colorectal cancer is the second leading cause of cancer death in the United States, with 49,960 deaths and 148,810 new cases expected in 2008.
Many people are so squeamish about tests for the disease that they skip them entirely. It is one of the very few cancers that can be entirely prevented by removing polyps or other precancerous growths or can be cured if detected early.
“Fifty percent of the population gets no screening,” said Dr. Grace H. Elta, a gastroenterologist and professor at the University of Michigan who is president of the American Society for Gastrointestinal Endoscopy. “Any screening is better than that.”
The new guidelines organize the tests in two groups and specify the intervals to perform them.
The first group consists of tests that can detect cancer or prevent it by finding precancerous growths. It includes colonoscopy, which examines the entire colon; flexible sigmoidoscopy, which examines part of the colon; barium enemas; and virtual colonoscopy.
The second group primarily detects cancer, rather than preventing it. Two tests look for blood in the stool, and the third is the stool DNA test. Blood in the stool does not necessarily indicate cancer but requires follow-up.
“Prevention should be the primary goal,” said Dr. Robert Smith, director of screening for the cancer society.
That would mean that the first group of tests is preferable. But Dr. Smith said some people were unwilling to have them or unable to afford them.
Right now, Dr. Elta said, insurers do not cover virtual colonoscopy, which she said costs $1,200 to $1,500. It is uncertain whether the new guidelines will lead to coverage changes.
None of the tests are perfect. Doctors who perform colonoscopy, for instance, may fail to see precancerous lesions. Virtual colonoscopy will probably fail to detect lesions that are flat, a type that is especially risky and more common in the United States than previously realized, researchers reported Tuesday in The Journal of the American Medical Association.
Tests for blood in the stool generally miss polyps and detect just half of tumors. Sigmoidoscopy does not reach the upper stretches of the colon.
As for the stool DNA test, Dr. Elta said, “It’s really not ready for prime time.” The test is not accurate enough, she said, and in many instances not reimbursed by insurers.
“Most people are not using it right now,” she said. “The biggest hope of all is if it ever gets good enough to pick up polyps. It’s the test with the most promise, but right now it has no efficacy at picking up polyps.”