PCA3 a More Specific Test for Prostate Cancer

Posted on June 4th, 2010 by

For the detection of prostate cancer, a new urine test known as PCA3 produces fewer false-positive test results than the commonly used prostate-specific antigen (PSA) blood test. These results were presented at the 2010 annual meeting of the American Urological Association.

Since the late 1980s, the primary screening tool for early detection of prostate cancer has been the prostate-specific antigen (PSA) test. While this test is widely used, it remains controversial, due to both false positive and false negative test results. Produced by cells in the prostate, PSA levels in the blood tend to be elevated in men who have prostate cancer. However, not all men with prostate cancer have elevated PSA, and not all men with elevated PSA have prostate cancer. PSA levels can also become elevated as a result of noncancerous conditions of the prostate.

Men who have elevated levels of PSA are often referred for a prostate biopsy in order to determine whether prostate cancer is present. Many of these biopsies are negative (show no evidence of cancer). A goal of research into prostate cancer testing, therefore, is to reduce the number of men who undergo unnecessary prostate biopsies.

PCA3 is a test that could potentially help guide decisions about the need for prostate biopsy. PCA3 (prostate cancer gene 3) is overexpressed in men with prostate cancer but not in men with noncancerous prostate problems. The PCA3 test measures PCA3 expression in a sample of urine.

In the current study, PCA3 was evaluated among 1,994 men with elevated serum PSA and/or an abnormal digital-rectal exam.[1] All men underwent prostate biopsy, and 42% were found to have prostate cancer.

  • The average PCA3 level was higher in men with prostate cancer than in men without prostate cancer. PCA3 level was also correlated with Gleason score and cancer volume.
  • The PCA3 test had higher specificity than the PSA test (i.e. was more likely to correctly classify men without cancer), but lower sensitivity (was less likely to correctly classify men with cancer). Overall, PCA3 was more strongly linked with the likelihood of prostate cancer than PSA.

In another study presented at the AUA meeting, researchers assessed the ability of a test for free circulating DNA (fcDNA) to predict the presence of prostate cancer.[2] The results indicated that high fcDNA was linked with an increased likelihood of prostate cancer.

Tests such as these may eventually help guide decisions about the need for prostate biopsy.

References:


[1] Crawford ED, Trabulsi EJ, Qian J et al. PCA3: A urine-based genetic assay for detection of prostate cancer in men with elevated PSA. Presented at the 2010 annual meeting of the American Urological Association. May 29-June 3, 2010. San Francisco, CA. Abstract 2105.

[2] Singal R, Gordian E, Ramachandran K et al. Serum free circulating DNA as a biomarker for prostate cancer diagnosis. Presented at the 2010 annual meeting of the American Urological Association. May 29-June 3, 2010. San Francisco, CA. Abstract 1736.

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