A better test for lung cancer?

A new test might enable doctors to catch lung cancers that are missed by a commonly used diagnostic tool.

Each year in the United States, about 300,000 people get a chest X ray that shows a suspicious spot in a lung. That's enough to warrant a bronchoseopy, in which a doctor inserts a lighted, flexible scope down a person's windpipe to visually examine the cells. "The procedure detects cancer in about 75,000 of these patients, but twice that many are ultimately diagnosed with lung cancer, some after years of follow-up" says Avrum Spira, a pulmonary care physician at Boston University School of Medicine.

To more quickly detect cancers that are missed by bronchoscopy, Spira and his colleagues scanned 22,500 genes in lung-lining cells and found that 80 are inordinately active or quiescent in cancerous cells compared with their behavior in normal cells.

To test whether this unusual genetic signature could predict cancer, Spira and his team enrolled 152 current and former smokers who had suspicious chest X rays. Each underwent a bronchoscopy. During the procedure, the researchers collected cells lining the windpipe to use for the genetic-signature test.

A final cancer determination was made after several months of follow-up and, in some cases, open-lung biopsy. The bronchoscopies had detected roughly half of the cancers in the group, and the genetic signatures of the windpipe cells had revealed 80 percent.

"By adding this test to the [bronchoscopy] procedure, we picked up almost 90 percent of the lung cancer cases," Spira says. The genetic test was especially good at catching cancer in an early stage, when it is most treatable.

Affymetrix of Santa Clara, Calif., which funded the study, has the patent for the genetic test.