(Reuters)
Updated: 2008-03-20 07:58

NEW YORK - Lung cancer is usually diagnosed at a late stage when it's difficult to cure, but someday a blood test may lead to earlier detection, researchers report.

The immune system produces antibodies that target antigens on lung tumors. Screening blood samples for these antibodies, using a panel of tumor-associated antigens, could identify people with lung cancer in the early stages.

Dr. Caroline J. Chapman, at The University of Nottingham in the UK, and colleagues there and in Germany evaluated blood samples from 50 healthy individual and 104 patients with lung cancer for levels of antibodies to seven cancer-associated antigens.

High levels of antibodies were found to at least one of the seven antigens in 76 percent of the lung cancer patients, Chapman's team reports in the medical journal Thorax. Among patients with cancer that was still localized and had not spread to the lymph nodes, antibodies were found in 89 percent of cases.

The researchers found that three of the antigens, which occur in several different types of cancer, "did not add significantly to the panel assay." Substituting other lung cancer-specific antigens for these general cancer antigens may improve the potential of the panel, they add.

"A diagnostic test for lung cancer is of particular importance owing to the late stage at which patients currently present with this disease and the fact that this disease will cause significant social burden for at least 20 years, even if all smoking were discontinued today," the researchers conclude.