TUESDAY, Jan. 23 (HealthDay News) -- U.S. researchers say a simple test that analyzes DNA in a person's sputum could be used to diagnose lung cancer.

As outlined in an article in the Jan. 15 issue of the journal Clinical Cancer Research, a team at the University of Maryland School of Medicine is developing an inexpensive and non-invasive genetic test to help detect early stage lung cancer in current and former smokers.

The test looks at whether two genes (HYAL2 and FHIT) -- believed to be tumor-suppressors -- are missing from cells found in sputum. The test, called "fluorescent in situ hybridization (FISH)," uses fluorescently labeled single-strand DNA probes to bind to the complementary band of a specific gene. A special microscope is then used to check for the presence or absence of a fluorescent signal produced when the strands bind.

An initial test of FISH identified 76 percent of stage 1 lung cancer patients whose tumors also showed the same loss of the two genes. In contrast, standard sputum cytology tests -- which look for changes in cell structure -- identified 46 percent of the patients.

"There is an urgent need to develop reliable early diagnostic biomarkers for lung cancer that can be detected non-invasively, and these two genes look to be great candidate markers for such a test," Dr. Feng Jiang, assistant professor of pathology, said in a prepared statement.

"We need to validate our finding, of course, but we have shown that the genetic aberrations seen in sputum reflect the same genetic aberrations found in lung tumors, and that these molecular changes occur before any morphological changes can be seen in a cytology test," Jiang said.

"As a diagnostic tool to identify early stage lung cancer patients who would then benefit most from curative therapies, FISH is very cheap and convenient," he said. "The technique may be also useful in monitoring lung cancer patients for response to treatment, disease progression and early evidence of relapse in the future."

More information

The U.S. National Cancer Institute has more about lung cancer.