Move Over, PSA - Here Comes EPCA-2

Robert W. Griffith, MD

Prostate-specific antigen (PSA) is a protein produced by the cells of the prostate gland. It's normal for men to have low levels of PSA in their blood; however, prostate cancer or some benign (i.e. not cancerous) conditions, such as prostatitis and prostatic hyperplasia can increase PSA levels.

Screening PSA levels regularly has been the standard of care for the last 20 years or so. But there are too many positive results necessitating a prostate needle biopsy, which can prove to be cancer-free in 80% - the so-called 'false-positive' cases. Clinical tests are 'scored' by their ratings for specificity and sensitivity (1).

Now there's a report of a new blood test that can improve the accuracy of prostate cancer testing, minimizing the number of false positives and reducing the number of unnecessary biopsies - and, as one who knows, I can tell you that this is a worthwhile goal! It's called the early prostate cancer antigen (EPCA)-2.

A report in the journal Urology claims that EPCA-2 is more specific (i.e. fewer false positives) and can distinguish between men with cancer confined to the prostate and those with spread outside the gland. The specificity of the new test was found to be 94% - a very acceptable level - for healthy men and those with benign prostate hypertrophy; this is much better than the PSA's 65%. And EPCA-2 had a sensitivity of 94% for overall prostate cancer - also better than PSA's sensitivity.

Clearly the new test is a considerable advance. Unfortunately it will not be available for another 1 to 2 years, so baby boomers should continue with their annual PSA and digital rectal exam for the time being.

(1) The sensitivity of a test is the proportion of those people who actually have the condition who have a positive test result. When a test has a high sensitivity, a negative result can help rule out the diagnosis. The specificity of a test is the proportion of people without the disease who have a negative test result. When a test has a high specificity, a positive result 'rules in' the diagnosis.

Source
HealthandAge Blog

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