Cancer immunomics: using autoantibody signatures in the early detection of prostate cancer

Prostate cancer remains the most common malignancy among men and the second leading cause of cancer death of men in the United States. Although measurement of prostate-specific antigen (PSA) has led to earlier detection of many prostate cancers, new serum biomarkers are still needed to improve the accuracy of prostate cancer detection. Considerable evidence has shown that an immune response in the form of autoantibodies to various tumor antigens develops in many patients with cancer. By using phage-epitope microarray analysis, we were able to identify peptides expressed by prostate cancer tissue, which commonly induce formation of autoantibodies in the sera of patients with prostate cancer. Using a panel of 22 peptides, we were able to detect prostate cancer with a specificity of 88.2% and a sensitivity of 81.6%. These results were significantly better than PSA, especially among men with a PSA between 4 and 10 ng/ml. Measurement of the immune response to prostate cancer, as well as other malignancies, has the potential to improve significantly the detection of these cancers and possibly assist in the determination of prognosis.