A new study shows that testing blood samples for antibodies that target prostate cancer cells may help identify patients with early stages of the disease.
Previous studies have found that men with normal blood levels of PSA (4.0 ng/ml or less) can have prostate cancer. Furthermore, PSA-based prostate cancer screening has a high rate of false-positive results (up to 80 percent). Therefore, scientists have been looking for additional ways to adequately screen for early disease.
The panel of 22 target proteins identified in this study showed an 88.2 percent specificity value for prostate cancer, which indicates the proportion of those tested who did not have cancer and were correctly identified as being free of disease. The test also showed an 81.6 percent sensitivity value, indicating the proportion of those patients with cancer that were correctly diagnosed as having prostate cancer.
Scientists know that cancer patients produce antibodies to proteins, called antigens, which are present on the surface of tumor cells.
The use of autoantibody signatures may be useful in combination with PSA testing in reducing the number of false negative and false positive tests obtained then when using PSA testing alone. Statistical analysis of these results shows that the protein panel performed better in distinguishing between prostate cancer patients and controls than the PSA test. The panel of 22 proteins predicted the presence of cancer accurately 92.7 percent of the time, while PSA predicted the presence of cancer only 79.6 percent of the time. The use of autoantibody signatures may be most informative in assessing the need for a biopsy in patients with PSA values of 10ng/ml or less.
Identification of autoantibodies is an exciting area of research.