Breath Test Detects Lung Cancer

It is possible to detect DNA methylation in the breath of smokers and lung cancer patients, suggesting that it may be possible to use this technique to identify people who have undiagnosed lung cancer or are at high risk of developing the disease. DNA methylation is a kind of chemical modification of the cell's DNA, a process known to be associated with lung and other cancers.

The assay simultaneously detects the presence of methylation in six tumor-suppressor genes. Methylation is a process by which a gene is chemically silenced. The assay examines the promoter region of a gene where certain cytosine nucleotide bases may be methylated, preventing the gene from being expressed. To test the assay, people were asked to breathe for 10 minutes into a commercially available device, which cooled the air and formed a condensed vapor. Next, an assay was applied that detects chemical changes--specifically, a DNA methylated form of tumor-suppressor genes.

"The breath test was successful in finding cancer markers,” said Dr. Simon D. Spivack, a pulmonologist at the Wadsworth Center, the public health laboratory of the New York State Department of Health (Albany, NY, USA). The assay was presented at the annual meeting of the American Association for Cancer Research, held in Boston (MA, USA) in November 2006.

Doctors have long sought a reliable early detection method for lung cancer. Even when something that looks like a predictor of cancer is found, such as a nodule on the lung during a CT scan, it is still not a foolproof way to determine who will get cancer, Dr. Spivack said. "What we find in middle-age smokers is that 20-80% of these people have nodules,” he said. "But 95% of the nodules are not cancer and are not going to be.”

"The concept of testing exhaled breath is not new--that [is] what breathalyzers do when they measure small volatile molecules such as alcohol, as well as inflammation molecules that are currently being assayed to test the activity of asthma and other lung diseases,” said Dr. Spivack. "But what is rather remarkable here is that DNA can be tested in the air that comes from the lungs and airways, and that it might be possible to use this in diagnosis of lung cancer in particular, and gene-dysregulation disorders of the lung, in general.”



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Wadsworth Center