Lung Cancer Molecular Markers

The invention provides a method of diagnosis and/or prognosis of lung cancer, the method comprising the steps of: (a) determining the level of a C4 activation fragment in a test sample, and (b) comparing the level of the test sample with the level of a C4 activation fragment detected in a control sample, wherein if the level of C4 activation fragment is higher than the level in a reference control, it is indicative that the subject suffers lung cancer or has a bad prognosis. The present invention further provides methods for determining the risk of suffering from lung cancer as well as for deciding whether to initiate a medical regimen and to determine the efficacy of said medical regimen, based on the determination of a C4 activation fragment. C4 activation fragment, used as marker, confers high sensitivity and specificity to the methods object of the invention.