The tests range in price from a few dollars to several hundred.
Which test is best for patients depend on several factors, including what their insurer covers and the preference of their primary care doctor, experts said.Only one company has a stool DNA test on the market - EXACT Sciences Corp. of Marlborough, Mass. The medical groups delayed releasing the recommendations until markets closed Wednesday because they were concerned it would affect trading, Brawley said.
The recommendations may also mean more business for radiologists. There has been something of a turf battle between gastroenterologists, who perform colonoscopies, and radiologists, who handle virtual colonoscopies.
The new guidelines represent an agreement that both are valuable ways to diagnose and prevent colon cancer, Brawley said.
These first consensus guidelines were released by the Cancer Society, the American College of Radiology, and the U.S. Multi-Society Task Force on Colorectal Cancer.
The latter group comprises representatives from the American College of Gastroenterology, the American Gastroenterological Association and the American Society for Gastrointestinal Endoscopy.
The recommendations came out the same day as a medical study that found that flat growths on the colon wall are more common in Americans than previously thought. Researchers concluded that the growths are more likely to be cancerous than the more familiar knobby masses known as polyps.
The study, published in the Journal of the American Medical Association, suggested that more careful colorectal cancer screening is necessary.
However, Brawley said the release of the new recommendations was coincidental and not driven by the study's findings.
Colorectal cancer is the nation's second leading cancer killer. It will kill about 50,000 people in the United States this year, the Cancer Society estimates. Screenings are designed to save lives by finding growths before they turn cancerous.
Traditional colonoscopies, long considered the gold standard test, are recommended every 10 years, starting at age 50. A doctor snakes a long, thin tube equipped with a small video camera through the large intestine to view the lining. The doctors also can use the device to cut away a tissue sample or even remove a polyp.
However, colonoscopies come with risks, including a chance that a doctor will accidentally puncture the colon. Also, many people have balked at getting screened because the test is expensive and they perceive it as unpleasant.
A virtual colonoscopy is a sort of super X-ray of the colon and rectum. Air is pumped into the colon to stretch it, and then a special CT scan is done. It is not invasive, but if a polyp is found, doctors will have to perform an optical colonoscopy in order to take a biopsy.
The biggest issue is not which screening a patient should get, but that patients come in for screening. All colon cancer deaths can be averted through screening and early treatment, but only 30 percent of people recommended to get screenings actually do, according to the Cancer Society.
"The challenge we have is getting people to participate in screenings," said Jack Mandel, an Emory University epidemiologist who has studied colon cancer screening tests. "We can prevent these deaths."
