Neil Canavan

September 13, 2013

BARCELONA, Spain — Electronic nose technology, first developed for the military to detect chemical warfare, analyzes breath exhalations and can identify lung cancer with a high degree of accuracy, investigators report.

"The advantages of such a test are many," said Maris Bukovskis, MD, from Pauls Stradiņš Clinical University Hospital in Riga, Latvia. "It would be cheap, easy to perform, noninvasive, and sufficiently accurate as an initial screen."

Dr. Bukovskis' team is now training the chemical sensors on the technology to detect volatile organic compounds in the breath of lung cancer patients. He presented the work to reporters attending a news conference here the European Respiratory Society (ERS) 2013 Annual Congress.

Lung cancer accounts for 1.3 million deaths annually worldwide. It kills is more than colon, breast, and prostate cancer combined, which are the next 3 most common forms of cancer.

"The prognosis even for early-stage lung cancer is not good, with less than 73% of patients surviving 5 years after diagnosis," Dr. Bukovskis reported. "The 5-year survival for stage III lung cancer is less than 25%; for metastatic lung cancer, the rate drops to less than 10%."

The poor prognosis has everything to do with a failure to detect the disease before it has a chance to progress. "The problem is that the available diagnostic methods are insensitive, expensive, or invasive, and not fit for general screening purposes," he noted.

"It's been shown that dogs are able to distinguish between breath samples of people with lung cancer and those with COPD with an accuracy of up to 71%," Dr. Bukovskis explained.

In addition, analyses performed with gas chromatography and mass spectrometers have distinguished between samples from lung cancer patients and healthy control subjects.

Dogs Can Also Detect Disease

However, Dr. Bukovskis pointed out, "dogs cannot be standardized and the analytical machines are cumbersome, too expensive, and much too time-consuming."

In this study, the e-nose sensors — which mimic mammalian sensory processes — were exposed to training sets of organic compounds from known lung cancer patients.

"We were not looking at specific markers," Dr. Bukovskis explained. The biomarkers for lung cancer are generally not known. "We really have no idea at this point which chemicals, and in what concentrations, are being detected to establish the smell print." However, the overall pattern of compounds is distinctive.

Once an imprint was established, the device was tested on 252 patients already diagnosed with lung cancer, 91 with other chronic lung conditions, and 79 healthy control subjects.

The e-nose had a positive predictive value of 91.4% for lung cancer in nonsmokers and of 94.2% in smokers. The average negative predictive value was 95.0% in both groups.

The average sensitivity overall was 96.0%, and the average specificity was 91.0%.

Although validation of the e-nose is a number of years away, given these results, Dr. Bukovskis said he is convinced that the technology will one day play a role in lung cancer screening programs.

Broader Applications

"I'm very interested in the potential of the e-nose for diagnosis and specific phenotyping of disease, and for the research potential in the investigation of chronic lung disease," said ERS president-elect Elisabeth Bel, MD.

"It would very helpful to understand the components of the volatile organic compounds print relative to lung cancer subtypes. That should be the ultimate goal, so that with just a breath, you could tell the patient you have adenocarcinoma, squamous cell carcinoma, and so on."

There are also broader applications of the technology. Dr. Bel is involved in the Unbiased Biomarkers in Prediction of Respiratory Disease Outcomes (U-BIOPRED) research project, which is using samples from adults and children to learn more about different types of asthma as part of the development of personalized medicine in respiratory disease.

"If you were able to detect that a patient is prone to severe asthma, for instance," she added, "that would have implications for disease treatment."

Dr. Bukovskis and Dr. Bel have disclosed no relevant financial relationships.

European Respiratory Society (ERS) 2013 Annual Congress: Abstract 1824. Presented September 9, 2013.

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