Breath test to identify the type of lung cancer

Researchers have developed a new breath test for diagnosing lung cancer in high risk patients. The test identifies the volatile organic compounds (VOCs) present in the exhaled breath to differentiate between the different types of lung cancer. It is especially useful in differentiating between squamouscell carcinoma and adenocarcinoma of the lungs. The test was presented in this year’s American College of Chest Physicians meeting.

Peter Mazzone, from the Cleveland Clinic, along with his associates, identified 236 patients with a high risk of developing lung cancer. The patients were above 40 years of age and had indeterminate lung nodules. The size of the nodules varied from4 to 20 mm in diameter. The nodules were either suspected to be malignant or had been proven malignant by biopsy but the treatment had not been started. 288 different patients were used to optimize the breath analyzing test developed by Mazzone and his team. 

The patients were made to inhale air passed through a filter to remove any VOCs. The test device was then used to capture only the air exhaled by the alveoli. This 4 liter of exhaled breath was passed through a colorimetric sensor array. This array uses pigments on a chip which change color in the presence of VOCs. Different colors can be used to differentiate between different types of VOCs. The researchers observed that the test was pretty accurate in diagnosing cases of lung cancer and its various sub-types. The C-statistics, calculated as the area under the operating characteristic curve were 0.828 for NSCLC, 0.824 for adenocarcinoma and 0.874 for squamous cell carcinoma.

On the basis of the results obtained in the clinical trial, the researchers have opined that the VOC profile can be used as a biomarker to identify different types of lung cancer. It is low cost and much fast, compared to pathological tests done after biopsy or surgery. The test can be used to identify patients for low dose CT scan, thereby reducing the number of false positive results. However, larger clinical trials are needed before the true value of the test is ascertained.

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Date: 
Thursday, October 31, 2013
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