Medical researchers say there's now a new way to test for colorectal cancer with a colonoscopy.
The new noninvasive screening test can detect most cases of colorectal cancer and many precancerous polyps, which could help reduce the death toll from the disease significantly, according to results of a study released on Thursday.
In its announcement about the study released Thursday, test developer Exact Sciences Corporation said its test detected 92 percent of the cancers detected by colonoscopy and 42 percent of potentially precancerous polyps, with a false positive --- or, inaccuracy --- rate of 13 percent.
The results nevertheless fell short of investor expectations and even those of the company that created the test, which sent Exact Science stock shares falling 20 percent, the New York Times reported.
The new test, called Cologuard, looks for alterations in human DNA found in stool samples.
Exact Science asserts people won't find it off-putting to deposit a sample of their stool in a company collection apparatus and mail it to a laboratory.
The new test, the company says, is not intended to replace colonoscopy, which remains the best method.
But about half of those over 50, the recommended age to start colorectal screening, are either not adequately tested or not screened at all, at least in part because colonoscopy is invasive, uncomfortable, expensive and time-consuming.
Exact Sciences says the noninvasive test could allow more people to be screened, while those who test positive could then also receive colonoscopies.
"For the first time noninvasively, we can detect reliably precancerous polyps," said Kevin T. Conroy, the company's chief executive.
Based in Madison, Wis., Exact Sciences said it would soon complete its application to the Food and Drug Administration seeking approval for the Cologuard test.
There were an estimated 143,000 new cases of colorectal cancer and 52,000 deaths in the United States last year, second only to lung cancer in cancer-related deaths, according to the American Cancer Society.
Exact Sciences said its study of Cologuard involved about 10,000 people with an average risk of colorectal cancer, screened at 90 sites in the United States and Canada.
Conroy said the 42 percent success rate in detecting polyps, while below the company's goal of 50 percent, was still a powerful result. Additionally, he said, the test caught 66 percent of polyps larger than two centimeters, which were more likely to become cancerous than smaller growths.