Natural Health

Non-Invasive Test May Detect Cancer and More

By: Drucilla Dyess
Published: Friday, 14 March 2008
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A new study shows how scientists can use laser light to detect faint breath molecules that could be “biomarkers” for disease. The study was led by University of Colorado at Boulder physics doctoral student Michael Thorpe and Jun Ye, a research fellow at JILA, a joint institute of the National Institute of Standards and Technology (NIST) and the University of Colorado at Boulder. Thorpe and Ye along with doctoral student Matthew Kirchner and former graduate student David Balslev-Clausen described their work in the February 18th online edition of Optics Express, published by the Optical Society of America.

The group has produced a machine that can identify single molecules that are associated with specific diseases through a person’s breath. Due to the findings of the study, it may one day be possible to visit your healthcare provider’s office and breathe into a device that will indicate if you are in an early stage of diseases ranging from lung cancer to asthma to kidney failure. This could have a huge impact on survival since early detection is key in successfully treating many medical problems and because some of these diseases first show their presence in the breath.

“It's very noninvasive,” said physicist, Ye. “There's nothing to be scared of. No blood test, just a breath test.” People exhale a mixture of gases, including oxygen, nitrogen, carbon dioxide, and others. “Researchers have already identified more than 1,000 of these molecules that exist on your breath, and they pertain to your metabolism, or maybe disease, or just the state of your health in general,” said Thorpe.

In addition to the gases and compounds, people exhale certain molecules that are considered biomarkers indicating specific conditions, such as diseases.

Since only a few of the trillions of molecules contained in normal breath are actual biomarkers, a pattern consisting of several different types of biomarkers that are all associated with a particular medical problem would have to be established for this type of device to be effective. And that, according to Ye, is exactly what his team has accomplished.

The core technology is a device called optical frequency comb. The optical frequency comb was developed in the 1990s by Ye's JILA, NIST and CU-Boulder colleague John L. "Jan" Hall and Theodor W. Hänsch of Germany's Max-Planck Institute, who shared the 2005 Nobel Prize in physics with Roy J. Glauber for their work.

The research group applied the technology to spectroscopy, which is used to identify distinct molecules by their emission and absorption of light. During a month long study, volunteers breathed into a “detection chamber.” The machine is about the size of a microwave oven containing a cavity between two curved mirrors. Laser pulses are shot into the cavity and reflect back and forth between the mirrors tens of thousands of times, bombarding any molecules in their way, before finally escaping. The information was then recorded on a camera, allowing researchers to actually see what was in the breath on a computer.

According to Ye, the findings were very precise. One of the participants was a smoker, and his test revealed five times the normal level of carbon monoxide. “If you have asthma, your breath will have nitrous oxide, but nitrous oxide does not necessarily mean you have asthma,” he said. “But if you see several different molecules all at once, and they are associated with asthma, then you have found a real fingerprint of a certain disease.”

The new technique has yet to be tested in clinical trails and the technology is currently limited to diseases that involve the lungs. But the hope is that applications could broaden as the technology develops further. “In the future hopefully we'll be able to tell things about kidney failure, liver failure, cancer and diabetes,” Thorpe said. "I hope it means a cheaper method for health screening. That would be the ultimate goal.”

The device can also differentiate between different isotopes such as carbon 12 and carbon 13 as well as oxygen 16 and oxygen 17. Changes in those ratios could indicate the presence of a disease. The idea is to build a system that will allow the earliest possible detection in the least invasive manner at a price that everyone can afford, according to Ye.

Ye also noted that excess methylamine could be a sign of liver and kidney disease, ammonia could be a sign of renal failure, elevated acetone levels could indicate diabetes and nitric oxide levels can be used to diagnose asthma just as bad breath is an indication of dental problems.