Breath tests have the potential to identify people with colorectal cancer, a small study suggests.

Researchers know that cancer tissue has a different metabolism compared with healthy cells that produce substances that can be detected in the breath non-invasively.

Researchers are looking for a non-invasive, accurate and low-cost screening for colorectal cancer. (Jean-Paul Pelissier/Reuters)

Breath analysis is already used to diagnose benign gastrointestinal disorders such as H. pylori infection or lactose intolerance.

To test the method for colorectal cancer, researchers in Italy collected breath samples from 37 people with colorectal cancer and 41 people without the disease and used a statistical model to compare the chemical fingerprints in the exhaled samples.

"The present findings support the value of breath testing as a screening tool," Dr. Donato Altomare, of the department of emergency and organ transplantation at the University Aldo Moro of Bari in Italy, and co-authors concluded in Wednesday’s issue of the British Journal of Surgery.

People with colorectal cancer showed a different pattern for 15 of 58 volatile organic compounds, their study suggested.

The researchers said their goal is to improve the diagnostic accuracy of blood and stool tests or virtual colonoscopy for early detection of colorectal cancer and polyps.

The study had two phases. In the first part, researchers identified the pattern of volatile organic compounds that could potentially discriminate patients from controls. Next, they validated the model on a series of 15 patients and 10 controls in a blinded test.

Overall, the accuracy was 76 per cent. But the model misclassified five out of 37 patients and seven of 41 controls.

The researchers said their next step will be to increase the number of subjects and hopefully simplify the formula to make it easier to use.