''Currently, 20% to 25% of surgeries done for suspected lung cancer turn out to be benign diagnoses," says Steven Dubinett, MD, professor of medicine and pathology and director of the Lung Cancer Research Program at the Jonsson Comprehensive Cancer Center at the David Geffen School of Medicine, University of California, Los Angeles. He is the senior author on the study, presented at the American Association for Cancer Research-International Association for the Study of Lung Cancer's joint conference in Coronado, Calif.
About 219,000 new cases of lung cancer were expected to be diagnosed in the U.S. in 2009, according to the American Cancer Society, and about 159,000 deaths were expected.
According to Dubinett, about one in 500 chest X-rays shows a lung nodule of ''indeterminant significance." When that occurs, the next step is to examine the suspicious area, with the physician ordering a biopsy or inserting a scope into the lungs to evaluate further.
Lung Cancer Blood Test: Study Details
Building on their own previous research and that of others, Dubinett and his colleagues assembled a panel of 40 potential lung cancer biomarkers -- substances found in the blood that can be measured and detected with blood tests.
These biomarkers, Dubinett says, are made up of proteins thought to contribute to lung cancer progression or whose levels may be changed as a result of the tumor. The thinking among experts studying these biomarkers is that they will be present in the blood of people who are in the very early stages of lung cancer.
The researchers took blood from 90 lung cancer patients and from 56 people at high risk for lung cancer because of a heavy smoking history who had quit for at least a year.
They found that 33 of the 40 biomarkers were different between the lung cancer patients and those not diagnosed with lung cancer. They found that the panel of biomarkers was accurate in identifying lung cancer patients 88% of the time. It also correctly identified patients who did not have lung cancer 79% of the time.
Then they evaluated whether the markers could help detect lung cancer in early stages -- a challenge overall in the diagnosis of lung cancer. They compared blood samples from 31 patients with stage I lung cancer to the patients not diagnosed. There were 21 markers different enough between stage I cancer patients and non-cancer patients to suggest the method is sensitive enough to detect tumors in early stages.
The results are preliminary, Dubinett says, and more testing and validation are needed. "It will take a couple more years of testing in an appropriate clinical setting," he tells WebMD. "It might take three or four more years before these tests are clinically available."
Several other investigators are working on a lung cancer blood test, looking at various markers to predict early-stage cancers.
Today, Rachel Ostroff of SomaLogic in Boulder, Colo., is expected to report on the company's SomaDx, a lung cancer blood test under development that relies on a signature of 12 proteins.
It can correctly identify lung cancer more than 90% of the time, she tells WebMD.
She estimates that at least a half dozen such tests are in development.
Blood Test for Lung Cancer: Second Opinion
The results ''look very promising," says Lyudmila Bazhenova, MD, a medical oncologist and assistant clinical professor of medicine at the University of California San Diego Moores Cancer Center, who attended the meeting and is familiar with the Dubinett research.
''A blood test will be very, very useful in those with a nodule on an X-ray or CT scan," she tells WebMD. Reducing the need for a lung biopsy is a substantial accomplishment. The need to order a lung biopsy to determine if a nodule is malignant understandably triggers anxiety in patients and physicians
"A lung biopsy is not as easy [to do] as a biopsy for breast cancer," partly because of the lung's location, she says.