"Most heavy smokers never develop lung cancer, even though cells in their airways show genetic damage," Jiang said. "The trick is to find the genes that are only cancer related."
The research group had previously identified a set of genes that were deleted in lung cancer tumors, and in this study, they tested three of them (HYAL2, FHIT, and SFTPC) in sputum samples taken from 38 patients with stage 1 non-small cell lung cancer, 36 cancer-free smokers and 28 healthy nonsmokers.
Given that sputum contains expectorated airway cells, the researchers asked each of the participants to cough into a cup first thing in the morning for three days. Investigators then examined the sputum with both traditional cytology and with fluorescent in situ hybridization (FISH). The FISH technique uses fluorescently labeled single-strand DNA probes to bind to the complementary strand of a specific gene. The presence, or absence, of a fluorescent signal produced when the strands bind can be detected and scored with use of a special microscope.
"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," Jiang 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."
They found that FISH could not detect deletions in the SFTPC gene in sputum, although it was absent in 71 percent of tumors. But the loss of HYAL2 and FHIT in a patient's tumor could be detected in that person's sputum. The investigators specifically found that HYAL2 and FHIT were deleted in 84 percent and 79 percent of tumors and in 45 percent and 40 percent of matched sputum, respectively. Comb
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Contact: Greg Lester
lester@aacr.org
267-646-0554
American Association for Cancer Research
18-Jan-2007