The PSA test is a blood test used to detect the presence of the prostate-specific antigen (PSA). The goal of PSA testing is to detect prostate cancers at an early stage when treatment is most likely to be effective. Recent debate over early prostate cancer detection techniques has caused the PSA test to come under fire. The American Urological Association (AUA) is concerned that this debate has cast doubt over a useful means of early prostate cancer detection. The AUA strongly supports the use of the PSA test. The AUA believes in informed patient decision making. They also believe all men over 50 and those at high risk, African Americans and those with family history of prostate cancer, should consider the test and discuss its benefits and limitations with their health care providers. Men at high risk should consider testing at age 40.

The following commonly asked questions are extracted from the February 2000 issue of Oncology.

What factors can affect PSA and should be considered in the interpretation of results?

The three most common prostate diseases, prostatitis, benign prostatic hyperplasia (BPH), and prostate cancer, can all be associated with elevated serum PSA levels. Strenuous physical activity and infections are known to cause secondary elevations of PSA. Some medications may suppress PSA levels and cause false negatives, it is important to convey medication information to your health care provider before testing. Saw palmetto, an herbal supplement often taken to prevent BPH, has not been shown to affect PSA. However, medical providers should also be informed of herbal supplements taken.

What sensitivity and specificity issues relate to PSA?

PSA testing in patients with normal serum PSA levels (4.0 ng/ml or less) has a sensitivity of about 67% to 80%. This means that about 20% to 30% of tumors may be missed using PSA alone. One way to improve sensitivity is to adjust the normal value for younger men. Men in their 40s should have a serum PSA of 2.5 ng/ml or less. Another way to improve sensitivity is to follow serum PSA values in an individual over time (PSA velocity). If a rising trend is noted, a prostate biopsy may be considered. Some investigators recommend a biopsy if a rise of 0.75 ng/ml or greater is detected in a year. The specificity of PSA testing is 60% to 70% when PSA is greater than 4.0 ng/ml which means that unnecessary biopsies may be performed 30% to 40% of the time if based on the PSA alone. Specificity can be improved by increasing the normal value for older men, using the free-to-total PSA ratio, and by adjusting the PSA density (accounting for the fact that larger prostates produce larger amounts of PSA). A urologist should be consulted for a prostate biopsy when any of the following are present: PSA is 4.0 ng/ml or higher, there is a significant rise in PSA from one test the next, or the digital rectal exam is abnormal.

In 2000, data in the medical journal Epidemiology showed a decrease in U.S. prostate cancer mortality rates in white men less than 85 years of age to levels below those in 1986. The PSA test was approved in 1986. Another recent report suggests a downward trend in prostate cancer mortality rates that coincide with an increase in PSA screening.

Although the test is not perfect and may lead some men to be overly concerned about prostate cancer, a visit to the urologist can put those fears to rest. Given the choice between reacting to a condition that can be easily monitored or remaining unaware of a life-threatening condition, the AUA chooses the first.

Reference: "Let's Move Forward, Not Backward," E. Darracott Vaughan Jr., M.D., America's Pharmacist, June 2002, p.19-21.

TAOS PHARMACY ALSO BELIEVES IN INFORMED PATIENT DECISION MAKING. WE PROVIDE A VARIETY OF SCREENING SERVICES INCLUDING THE PSA TEST, CHOLESTEROL TESTING, DIABETES SCREENING, AND OTHERS. LET US HELP YOU MAKE INFORMED DECISIONS ABOUT YOUR HEALTH CARE.

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