Researchers at Johns Hopkins University School of Medicine have developed a new blood test for prostate cancer, which in a preliminary study proved better than the PSA test at identifying which men have cancer. The new test measures levels of the protein EPCA-2, which — unlike PSA — is produced almost exclusively by cancerous tissue.
The researchers measured EPCA-2 levels in 385 men with varying PSA levels who had all previously had prostate biopsies. Some men had cancer, while others did not. EPCA-2 levels were within the normal range in all of the men who were cancer-free, even when PSA levels were 2.5 ng/ml or greater, indicating that the EPCA-2 test could be used to avoid unnecessary biopsies. Yet the test may also help to identify which men with normal PSA tests actually have cancer: EPCA-2 levels were elevated in 14 of 18 men known to have prostate cancer whose PSA tests were under 2.5 ng/ml. The EPCA-2 test also appears to be highly accurate at distinguishing cancer confined to the prostate from that which has spread beyond the gland. Further research is needed to confirm the value of this test, but so far the results are promising.
Source: Leman ES, Cannon GW, Trock BJ, et al. EPCA-2: A Highly Specific Serum Marker for Prostate Cancer. Urology 2007;69:714–20. PMID: 17445657.