Mouth Swab May One Day Diagnose Lung Cancer

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For their lung cancer investigation, Mao and his colleagues examined and compared harmful genetic modifications in a total of 1,774 mouth and lung tissue samples taken from 127 chronic smokers participating in a larger cancer prevention study.

In the sampled DNA, the researchers looked for evidence of a harmful molecular change that short-circuits the function of two genes normally effective at halting tumor growth.

After two analyses conducted over a three-month period, the researchers found that tissue damage of this kind was present almost equally in both mouth and lung tissue. In theory, this makes oral cavity sampling nearly as effective as lung tissue sampling for diagnosing lung cancer.

"There were some folks who didn't show abnormalities in their oral tissue even when there were some in the lung tissue," Mao cautioned. "And we do have more research to do. But I already think it's a very important finding, in that this opens the door to a noninvasive diagnostic method."

He added, however, that it will "take some time" before a practical diagnostic tool based on the current observations can be designed.

Stanton A. Glantz, a professor of medicine and director of the Center for Tobacco Control Research and Education at the University of California, San Francisco, called Mao's line of inquiry "interesting," but as a diagnostic application "not ready for prime time."

"I would put this in the category of interesting observations that might lead somewhere, but I'm skeptical," he said. "Certainly, they might be on to something. And there's clearly a relationship between the molecular changes in the cells in the mouth and the lungs. They're clearly correlated with each other, which means they tend to increase together. But whether or not the relationship is tight enough in an individual patient to be useful in diagnosis is still way too early to tell."

"But it may well be that as they [the researchers] refine something like this, it might end up helping to identify patients at risk who are worth investigating further," Glantz added.

More information

To learn more about lung cancer, visit the American Cancer Society.