A new kind of test that finds evidence of colon cancer in the stool can also detect pre-cancerous growths and could potentially be an alternative to colonoscopies, researchers reported Thursday.

Exact Sciences’ new test detected 87 percent of stage I, II and III colon tumors, which can be surgically removed, and found 64 percent of the biggest pre-cancerous growths, the researchers told a meeting of the American Association for Cancer Research.

It finds altered DNA that has turned a cell cancerous or has started the changes that lead to cancer.

“The noninvasive stool DNA test we have developed is simple for patients, involves no diet or medication restriction, no unpleasant bowel preparation and no lost work time, as it can be done from home,” said Dr. David Ahlquist of the Mayo Clinic in Rochester, Minn., who developed the test. “Positive tests results would be followed up with colonoscopy.”

Mayo has licensed the test to Exact Sciences, which believes it has the potential to reach sales of $1 billion in the United States alone.
The test looks for three genes that have been altered in a process called methylation.

Colorectal tumors develop in the lining of the colon and in the rectum. As fecal matter passed through the tract, it collects some cells from these growths. The test can find even tiny amounts of altered DNA from these growths in a stool sample.

Studies of 1,100 patients showed the test detected 64 percent of precancerous growths called adenomas that were bigger than 1 cm (0.4 inch), which is considered the size most likely to turn into a tumor.

It found 85 percent of cancers, and 87 percent of the earlier stage cancer that can be cured by surgical removal.