Plasma proteomic profiling: search for lung cancer diagnostic and early detection markers

Environmental and occupational exposure to asbestos is among the established risk factors for lung cancer, the leading cause of cancer-related deaths in the United States. This link between exposure to asbestos and the excessive death rate from lung cancer was evident in a study of former workers of an asbestos pipe insulation manufacturing plant in Tyler, TX. We performed comparative proteomic profiling of plasma samples that were collected from nine patients within 12 months before death and their age-, race- and exposure-matched disease-free controls on strong anion exchange chips using surface-enhanced laser desorption ionization time-of-flight mass spectrometry. A distance-dependent K-nearest neighbor (KNN) classification algorithm identified spectral features of m/z values 7558.9 and 15103.0 that were able to distinguish lung cancer patients from disease-free individuals with high sensitivity and specificity. The high correlation between the intensities of these two peaks (r=0.987) strongly suggests that they are the doubly and singly charged ions of the same protein product. Examination of these proteomic markers in the plasma samples of subjects from >5 years before death from lung cancer suggested that they are related to the early development of lung cancer. Validation of these biomarkers would have significant implications for the early detection of lung cancer and better management of high-risk patients.