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Breath test for lung cancer

Donna G

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We have heard how smart dogs are smelling lung cancer but now perhaps we are closer to a screening test for lung cancer!

Laser can detect diseases in your breath

Device identifies compounds that may indicate cancer, asthma, study shows

A new laser technique could enable doctors to detect certain diseases, such as lung cancer or asthma, simply by analyzing a patient's breath.

A new study shows the laser system can identify trace levels of compounds that may be signs of disease in breath samples, and companies and investors have already expressed interest in developing the device for routine use in doctor's offices, said Jun Ye, a physicist at JILA, a joint institute of the National Institute of Standards and Technology and the University of Colorado at Boulder, who led the research.

The advantages of the laser technique — known as optical frequency comb spectroscopy — is that it would provide a painless and non-invasive way of detecting certain diseases. In addition, it could enable physicians to detect some conditions earlier when they may be more easily treated, Ye said.

With each breath, we exhale a variety of chemicals. The predominant compounds are carbon dioxide and oxygen, but a typical exhalation will also contain more than a thousand other chemicals in very tiny amounts, some of which can indicate disease. For example, ammonia could be a sign of kidney failure, while nitric oxide can indicate asthma.

Breath analysis systems have been around for several years, but a common problem with previous methods is they could only detect one or a few types of compounds in the breath. This doesn't provide enough information to determine if a person has a specific disease because they could have elevated levels of a single compound for other reasons, Ye said.

But the new laser technique provides a way to assess the levels of many different compounds in the breath at once, offering a more accurate picture of whether a person has a particular disease. “It's like seeing the entire forest, rather than just individual trees,” Ye said.

In the study, which was published in this week's Optics Express, Ye's team had human volunteers breathe into the laser system. The device reliably detected trace levels of methane, carbon monoxide and carbon dioxide in the breath samples. The device was able to detect higher levels of carbon monoxide in the breath of a smoker compared to a non-smoking participant. The device also distinguished ammonia — an indicator of kidney failure — from water, which can be a tricky issue because of the similarity of the compounds.

The next step is larger trials to show the technique can accurately diagnose diseases.

The technique would be most useful for detecting lung problems, such as lung cancer and asthma, because these conditions create changes in the body that show up in the breath, Ye said. It also could be used for digestive problems because these can lead to alterations in the composition of the breath.

Immediate results

To use the device, a person breathes into a tube into which a laser is shining. Mirrors positioned around the tube reflect the laser signal to enhance detection of compounds. The laser signal bounces off the different chemicals in the breath sample, and the device is able to detect the unique light signals of specific compounds.

“It's almost like a radio,” Ye said. “Each molecule has a unique set of frequencies, like a certain radio station, so the device can easily identify them.”

The results are nearly instantaneous, he said. So there's no need to wait for an analysis to be processed, as there is with a blood test.

Dr. John Hunt, a pediatrician at the University of Virginia in Charlottesville who has been involved in breath analysis research for more than 15 years, said the study results were promising but a lot of kinks need to be worked out before the laser technique could be used in patients. He said it still remains to be shown that the technique provides reproducible results and that the breath chemicals it detects can be used to accurately determine whether a person has a specific disease or not.

“It's an interesting early study with a very long way to go,” said Hunt.

More personalized treatment

He noted that the laser system has the potential to improve the treatment of some conditions, such as asthma, which have numerous different causes. Being able to analyze all the different compounds in the breath simultaneously may help pinpoint the specific cause of a person's asthma and enable physicians to develop a personalized treatment instead of treating each patient exactly the same, Hunt said.

So far, Ye said, at least one physician and two companies, including a local Colorado firm and one in Germany have contacted him about their interest in developing his laser technique for use in patients.

The system may have other important applications as well. Ye said the Los Alamos National Laboratory in New Mexico has said they're interested in developing the technique for use in airport security screenings to detect explosives or nuclear material in the ambient air. And the Jet Propulsion Laboratory in Pasadena, Calif., is considering whether it could be used on remote locations, such as the surface of Mars, to detect the composition of the air in these environments.

Steve Mitchell is a science and medicine writer in Washington, D.C. His articles have appeared in a variety of newspapers, magazines and Web sites, including UPI, Reuters Health, The Scientist and WebMD.

© 2008 MSNBC Interactive

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