The US health regulator has approved the first DNA-based test for colon cancer, which has proven to be more accurate than traditional tests.

The US Food and Drug Administration has approved the first screening test for colon cancer that uses patients' DNA to help spot potentially deadly tumours and growths.

The Cologuard test from Exact Sciences detects irregular mutations in stool samples that can be an early warning sign of cancer. Patients who test positive for the mutations should undergo a colonoscopy to confirm the results.

Doctors have long used stool tests to look for hidden blood that can be a warning sign of tumours and precancerous polyps.

But company studies of Cologuard showed that it was more accurate at detecting cancerous tumours and worrisome polyps than traditional stool blood tests.

Cologuard detected 92 per cent of colon cancers and 42 per cent of advanced polyps in a study of 10,000 patients, while traditional blood screening only detected 74 per cent of cancers and 24 per cent of advanced polyps.

The new test was not superior on all counts though. Cologuard was less accurate than older blood tests at correctly ruling out cancer, reporting more growths when none were actually present.

The approval has the potential to reshuffle current medical practice, though FDA officials stressed on Monday that DNA-based stool screening has not been endorsed by federal medical advisers who set screening guidelines. A spokeswoman for Exact Sciences, which is based in Madison, Wisconsin, said the new test would cost $US599 ($A648) per patient. That compares to about $US25 for a traditional stool blood test.

Current federal guidelines recommend traditional stool tests every year and a colonoscopy every 10 years for patients between ages 50 and 75. Colonoscopy is the most accurate method for spotting colon cancer but many adults are reluctant to undergo the invasive procedure, which requires sedation as doctors probe the colon with a camera-fitted endoscope.

Colorectal cancer is the second leading cause of cancer death in the US, with over 50,000 deaths expected this year, according to the American Cancer Society. Deaths from the disease have been declining for more than two decades, a development attributed to increased screening. Still, only about 60 per cent of people between ages 50 to 75 have had the recommended tests.

Copyright AAP 2014