A blood test that detects antibodies against prostate cancer cells more accurately identified prostate cancer than the test for prostate specific antigen (PSA), according to a study published in the New England Journal of Medicine .
The prostate is a gland of the male reproductive system. It produces some of the fluid that transports sperm during ejaculation. After skin cancer, prostate cancer is the most common form of cancer diagnosed in men.
Men 50 years or older in the US are often offered PSA testing for the early detection of prostate cancer. The PSA test measures proteins that are produced and shed by the prostate. PSA levels are elevated when prostate cancer is present, but levels can also be elevated in benign (non-cancerous) conditions affecting the prostate. A concern about use of the PSA test is that false positive results (elevated PSA in response to non-cancerous conditions) can lead to unnecessary biopsies. Researchers are therefore interested in identifying more accurate tests for the early detection of prostate cancer.
One method being explored for early prostate cancer detection is the identification of an immune response against cancer cells. In addition to fighting infections, the body’s immune system can also respond to threats such as cancer. Identification of an immune response that is present in most men with prostate cancer and absent in most men without prostate cancer could lead to a new approach to prostate cancer screening.
In order to test an antibody-based approach to prostate cancer detection, researchers analyzed serum samples from 119 men with prostate cancer and 138 men without prostate cancer. The antibody test that they used was positive in 82% of the men with cancer and negative in 88% of the men without cancer. The accuracy of the antibody test was higher than the accuracy of the PSA test.
The researchers conclude that tests for antibodies against prostate cancer cells could form the basis for a new and better approach to prostate cancer screening. Additional studies will be needed to confirm these results and to determine whether the complex technology behind this test can be transformed into a cost-effective screening tool for widespread use.
Reference: Wang X, Yu J, Sreekumar A et al. Autoantibody signatures in prostate cancer. New England
Journal of Medicine . 2005;353:1224-35.