University of Colorado at Boulder physics doctoral student Michael Thorpe holds a detection chamber while standing next to a laser apparatus in a photo released by the university on Tuesday. A new laser analyzer might be able to help doctors detect cancer, asthma or other diseases by sampling a patient's breath, researchers reported on Tuesday.

By blasting a person's breath with laser light, U.S. scientists have shown that they can detect molecules that may be markers for diseases like asthma or cancer.

While the new technique has yet to be tested in clinical trials, it may someday allow doctors to screen people for certain diseases simply by sampling their breath, according to the research team from JILA, a joint institute of the National Institute of Standards and Technology and the University of Colorado at Boulder as quoted by media Wednesday.

"This technique can give a broad picture of many different molecules in the breath all at once," Jun Ye, who led the research at the University of Colorado, said in a statement.

Ye's team developed a new technique, called cavity-enhanced direct optical frequency comb spectroscopy.

When animals and people breathe out, they exhale not only gases that are not needed, such as carbon dioxide, but also compounds that result from the metabolism of cells.

"To date, researchers have identified over 1,000 different compounds contained in human breath," Ye's team wrote in areport.

Some point to abnormal function -- such as methylamine, produced in higher amounts by liver and kidney disease, ammonia produced when the kidneys are failing or elevated acetone caused by diabetes.

People with asthma may produce too much nitric oxide, exhaled in the breath, while smokers produce high levels of carbon monoxide.

In 2006, researchers found dogs could be trained to smell cancer on the breath of patients with 99 percent accuracy.

Ye's team used their method to analyze the breath of several student volunteers and found they could detect trace signatures of ammonia, carbon monoxide, and methane in breath.

(Agencies via Xinhua News Agency February 20, 2008)