Immunodiagnostic Value of Combined Detection of Autoantibodies to Tumor-associated Antigens as Biomarkers in Pancreatic Cancer

Previous studies demonstrated that cancer sera contain antibodies, which react with a unique group of autologous cellular antigens called tumour-associated antigens (TAAs). This study determines whether a panel of TAAs would enhance antibody detection and be a useful approach in pancreatic cancer (PC) detection and diagnosis. The panel of TAAs was composed of six TAAs including p53, p16, p62, survivin, Koc and IMP1 full-length recombinant proteins. Enzyme-linked immunosorbent assay (ELISA) was used to detect antibodies against these six TAAs in 23 sera from patients with PC and also 23 sera from normal individuals. Antibody frequency to any individual TAA in PC was variable and ranged from 14.7% to 30.4%. With the successive addition of TAAs to a final total of six antigens, there was a stepwise increase in positive antibody reactions reaching a sensitivity of 60.9% and a specificity of 87.0% in PC. Positive and negative likelihood ratio were 4.685 and 0.449, respectively. Positive and negative predictive values were, respectively, 82.4% and 69.0%. Agreement rate and Kappa value were 73.9% and 0.478, respectively. The data from this study support our previous hypothesis that using a panel of appropriately selected TAAs can enhance autoantibody detection in immunodiagnosis of PC. In 15 PC sera with carbohydrate antigen 19-9 (CA19-9) negative, 6 (40%) were found to have anti-TAA (anti-tumour associated antigens) antibodies. When CA19-9 and anti-TAAs were used together as markers in PC detection, the diagnostic sensitivity could be raised from 60.9% to 69.6%. Anti-TAA and CA19-9 were independent markers, and the simultaneous use of these two markers could raise the sensitivity of PC detection.