TORONTO — Gene expression profiling of peripheral blood lymphocytes successfully identified lung cancer patients with an overall accuracy of 87% in a cross-sectional study of 230 subjects.
The test, which is in the early development stage, had a sensitivity of 85% and a specificity of 87%, Dr. Anil Vachani said at an international conference of the American Thoracic Society. Of the 230 subjects, 140 had lung cancer and 90 did not.
Lung cancer is difficult to diagnose. Many patients have lung nodules detected incidentally on chest x-ray or CT scan. The next step is problematic, as needle biopsy of the chest is difficult and bronchoscopy requires anesthesia and is risky. Often, the nodule is surgically removed and found to be benign, Dr. Vachani of the University of Pennsylvania, Philadelphia, said in a press conference.
A blood test for a patient who has a lung nodule would be useful. Other researchers have worked on this, but most have focused on finding a signature protein secreted by tumor cells into the bloodstream. But lung cancer is a more heterogeneous cancer, and no single protein has been found to identify all types of the disease, said Dr. Vachani.
He and his colleagues profiled “gene expression in peripheral blood mononuclear cells that are involved in tumor immunity” by isolating lymphocytes from peripheral blood and performing global gene expression profiling. “We measured the 20,000 genes found in these cells, and using advanced statistical algorithms, identified genes that are differentially expressed between patients and controls. We then see if we can validate whether genes that are differentially expressed can actually predict which patients have cancer and which do not.” The study was funded by the Pennsylvania Department of Health.