High PGP9.5 autoantibodies can indicate that a patient is at risk for lung cancer. PGP9.5 is a member of the ubiquitin peptide carboxy-terminal hydrolase class, which is associated with ubiquitination of the cell cycle, disordered growth of undifferentiated cells, and can influence cell growth and death. PGP9.5 is often expressed in neuronal cells, but it can also be expressed in large quantities in cancer cells of primary and secondary lung cancer, so the results of detecting the expression of PGP9.5 autoantibodies in the body can assist in the diagnosis of whether or not lung cancer is present. If the test result shows that PGP9.5 autoantibodies are high, it is recommended to undergo further examination to confirm the diagnosis.