Improved PSA Tests a Better Gauge of Prostate Cancer Risk

ROCHESTER, Minn. — A prostate-specific antigen (PSA) test can’t diagnose prostate cancer, but results indicate the risk of cancer. According to the January issue of Mayo Clinic Health Letter, recent fine-tuning of this test gives doctors better information to help determine cancer risk.

PSA is a substance produced in the prostate gland. Normally, a small amount of PSA enters the bloodstream. A higher amount or an abrupt rise in PSA levels can indicate a problem, possibly cancer.

However, PSA results aren’t specific; that is, a high PSA indicates increased risk of cancer, but not the presence of cancer. Nor does the risk information indicate how quickly a potential cancer might be growing. Most prostate cancers are slow growing. For older men, a slow-growing cancer may not cause symptoms and may never need treatment.

While not perfect, annual PSA testing, along with a digital rectal exam, remains the best option to detect prostate cancer early. Ask your physician about these recent refinements in PSA testing:

PSA velocity: This charts the change in PSA levels over time. PSA levels tend to increase more quickly in men who have prostate cancer than those with other prostate conditions. For example, an enlarged prostate, a benign condition, also can be indicated by increased PSA levels. Velocity testing is a reason why annual or more frequent PSA measures are important, because it shows subtle changes that can lead to early intervention and better outcomes.

PSA doubling time: Similar to PSA velocity, this test looks at how quickly PSA levels double. The risk of prostate cancer is particularly acute when PSA levels double within 18 months.

PSA density: Using ultrasound imaging, the physician determines the size of the prostate gland. With this data, the physician can evaluate the PSA number based on the gland’s size. For example, larger prostate glands produce more PSA.

Free versus total PSA: This test separates PSA in the bloodstream into two types. Bound or total PSA is attached to certain blood proteins, and free PSA isn’t. Prostate cancer is more likely to result from bound PSA. So, a lower percentage of free PSA compared to bound indicates an increased likelihood of cancer.

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