SERUM P53 ANTIBODIES AS EARLY MARKERS OF LUNG-CANCER

The p53 alteration is the most common alteration found in human cancer . It usually involves missense mutations that stabilize the p53 protei n, which in turn accumulates, reaching levels detectable by immunohist ochemistry. We(1-4) and others(5-8) have demonstrated that this overex pression of mutant p53 protein can induce a specific humoral response in cancer patients. This result was assessed by the presence of p53 an tibodies in sera of patients with various types of cancers, whereas no rmal populations do not exhibit such antibodies. In lung cancer, the p revalence of p53 antibodies is high (30%) and is correlated with a ver y high rate of p53 mutations in this cancer (60-70%)(2,8). We show tha t these antibodies are always present at the time of diagnosis, but ne ver appear during tumour development, an observation strengthened by t he fact that these antibodies are mostly IgG, corresponding to a secon dary immune response. These results suggest that the humoral response is an early event and that p53 antibodies can be used as a precocious marker of p53 alteration before clinical manifestation of the disease.