Researchers in the US are confident that a newly discovered protein early prostate cancer antigen-2 (EPCA-2), will become the biomarker for a more reliable blood based prostate cancer test.

Currently, prostate cancer testing relies on a PSA Test. Generally, if PSA levels are greater than 2.5 ng/mL a man is referred for a biopsy. This process is relatively unreliable because of three reasons:

• As high as 80 percent of men who get prostate biopsies due to elevated PSA do not have cancer.
• As high as 15 percent of men who have prostate cancer have negative PSA levels so their cancer goes undetected.
• A PSA test cannot tell if the prostate cancer has spread to other parts of the body.

According to a study published in Urology, The researchers tested the blood of over 300 men for their EPCA-2 and levels, and grouped them as follows:

• Normal PSA with prostate cancer
• Normal PSA without prostate cancer
• Elevated PSA and negative biopsies
• Men with benign prostatic hypertrophy (BPH) without biopsies
• Prostate cancer that has not metastasized
• Prostate cancer than has metastasized
• Men with other types of cancer
• Men with other non cancerous organ conditions

The EPCA-2 levels were tested on these patients, and the following results were found:

• 97 percent of patients who did not have prostate cancer were identified correctly
• Men with negative biopsies (no matter their PSA levels) had EPCA-2 levels considered normal
• Men with other types of cancer or benign organ problems all had EPCA-2 levels considered normal
• 94 percent of men with prostate cancer had alerting levels of EPCA-2
• 90 percent of those with stage I or stage II localized prostate cancer had alerting levels of EPCA-2
• 98 percent of men with metastasized prostate cancer had alerting levels of EPCA-2. These levels were so high, it appears to be able to differentiate between metastatic and non-metastatic prostate cancer
• 77 percent of the men with BPH had non-alarming levels of EPCA-2 which is within the approximate percentage estimated to be prostate cancer free.

This data shows that the EPCA-2 test is more sensitive and specific than the PSA test, and can accurately identify if the prostate cancer has metastasized or not. Larger studies are planned in the very near future, and the EPCA-2 test should be available for use in the US in about 18 months.

Analysis: If the results ot this study should be verified with larger research studies, the test will probably be used in conjunction with a PSA test and DRE for several years in order to completely verify its sensitivity and specificity. Ultimately, it could reduce the number of biopsies that men must endure in order to rule out prostate cancer.

_{Source: E. Leman, G. Cannon, B. Trock, L. Sokoll, et. al. (2007). EPCA-2: A Highly Specific Serum Marker for Prostate Cancer. Urology. 69(4); Apr 2007. 714-720. doi:10.1016/j.urology.2007.01.097}