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Abnormal PSA Levels

The National Cancer Institute estimates that more than 190,000 men will be diagnosed with prostate cancer in 2009. It is the second most common form of cancer in men. Testing for prostate-specific antigen levels, or PSA, is a screening tool used for the early detection of prostate cancer, and to monitor whether cancer has reoccurred in men who were successfully treated. The PSA test is usually performed in combination with a digital rectal exam (DRE).

  1. What Are PSA Levels?

    • PSA is measured in nanograms per milliter of blood (ng/mL). According to the Prostate Cancer Foundation, normal levels are below 4 ng/mL, and readings over 10 ng/mL are high. Results between four and 10 are called intermediate. However, doctors are more recently looking at the rate of change in PSA as a more accurate indicator of whether further testing is needed. At this time, an increase of 0.75 per year is acceptable, but a greater increase would require additional testing.

    Frequency Recommendations

    • The U.S. Food and Drug Administration approved the use of PSA tests as a yearly screening in men over 50. Many doctors concur, according to the NCI. However, when risk factors such as family history of cancer are present, some physicians recommend screenings beginning up to 10 years earlier.

    Factors Affecting PSA

    • A raised PSA level does not automatically mean cancer, as other factors can contribute to a higher number. Mayo Clinic indicates that elevated levels also can be caused by infection or inflammation. Benign prostate hyperplasia, which is non-cancerous enlargement of the prostate in older men, is another cause of raised PSA. If other risk factors are absent and the DRE was normal, some physicians recommend a period of "watchful waiting" and retesting for PSA before ordering more invasive tests such as biopsy.

    Limitations

    • Although it is a useful screening tool combined with a DRE, the PSA test is not a definitive means of detecting prostate cancer. According to Medicinenet.com, some men show normal readings even when cancer exists because insufficient levels of PSA are being produced. NCI reports that some cancers can exist for many years without affecting PSA levels. False positive results also occur, according to NCI. Of men who had biopsies following high PSA test results, 25 to 35 percent were found to be cancer-free.

    Test Improvements

    • Ongoing research seeks to determine ways in which the PSA test can be improved. PSA velocity (the rate of increase in PSA levels) is being considered as a more accurate measure than PSA levels alone. Another improvement under investigation is measuring attached PSA, which is connected to a protein molecule as it circulates through the blood. Presently, tests measure free PSA, which is not attached to a molecule. Researchers believe specifically measuring attached PSA, which is produced by cancer, would be a better diagnostic tool than measuring free PSA, which is also produced by benign enlargement of the prostate.

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