Molecular messages and signals circulating in blood or contained in cells lining the airway can identify early stage cancer, according to research reported today at the 2007 Annual Meeting of the American Association for Cancer Research.
A series of quietly exhaled breaths might indicate whether or not a patient is at risk for lung cancer, according to researchers from the New York State Department of Health. Using DNA recovered from exhaled breath, researchers can examine the state of cells that line the lungs, and potentially detect cancer at an early stage, when treatment may be most successful.
"Early detection of lung cancer is vital, yet there is no current non-invasive means of identifying cancer in a clinical setting," said Simon Spivack, M.D., M.P.H, research physician in the Human Toxicology & Molecular Epidemiology Laboratory at the New York State Department of Health's Wadsworth Center. "We have found that exhaled breath contains DNA, we believe from the cells lining the lungs, which may then tell us whether that person is at risk for cancer."
Condensed exhaled breath has been used previously to detect small volatile molecules that could indicate both non-malignant and malignant, lung diseases. Dr. Spivack and his colleagues have shown, in a pilot study, that the large molecule DNA could also be recovered albeit in trace amounts in exhaled breath condensate.
In particular, the researchers looked to see if the DNA they captured had been methylated, that is, tagged by a molecular "methyl" fragment, which blocks activation of the genes. The researchers analyzed the detailed methylation patterns of six tumor suppressor gene promotors, regions of DNA that serve as regulators of gene transcription. When those promoter regions become methylated, the cell can no longer activate its tumor suppressor genes.
It is not necessary to methylate every promoter region to induce cancer, the researchers say, so they study detailed variations in the patterns of methylation among selected gene promoters in different patients. Dr. Spivack and his colleagues believe that categorizing patients according to these methylation patterns can potentially evaluate a patient's predisposition to lung cancer. The pilot study of 33 individuals showed statistically apparent differences between never-smokers, former and current smokers, and those with lung cancer.
According to Dr. Spivack, their findings could represent a considerable advance in the early detection of lung cancer. He posits a scenario in which breath or other non-invasive tests such as CT scans can serve as cost-effective pre-screening tools for lung cancer, and could allow for treatment at early stage when the patient would theoretically have the best chance of success.
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