High PSA Level? Check it Again
PSA Tests Can Produce False Positives; Repeat Test After Six Weeks Advised
WebMD News Archive
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May 27, 2003 -- The PSA blood test is commonly used to check for signs of prostate cancer or other prostate problems. When a PSA level comes back high, the next step is often a biopsy. But a new study suggests another course of action: Another PSA test done more than a month later.
That's because PSA levels can fluctuate up and down -- so a man with a high PSA level may not actually have any prostate problems at all. In fact, after studying nearly 1,000 men, researchers found that about half of those whose PSA levels were initially high had a normal result in a subsequent test.
But unfortunately, says the study's lead researcher, James Eastham, MD, FACS, of Memorial Sloan-Kettering Cancer Center, the initial finding of an elevated PSA is enough to warrant one of three typical responses from doctors.
"The first scenario, and a common one, is that the patient is referred for a biopsy, which may be unnecessary and painful," Eastham tells WebMD. "The second is that the PSA is immediately repeated, within a week or so. But that will only take into account any possible lab error, since it's not enough time to get a handle on natural fluctuations. And the third scenario is that the patient is assumed to have inflammation or infection in the prostate, and put on antibiotics or anti-inflammatory drugs."
Instead, Eastham suggests taking no action until another test is done four to six weeks later -- a time period that he says allows for a natural decrease in fluctuating PSA levels.
"The bottom line is that the recommendation for a biopsy should not be based on a single elevated test result, and a second test shouldn't be given too soon after the first," he says.
In fact, even after a second test produced elevated PSA levels, biopsy detected prostate cancer in only one of four of study participants, according to Eastham's findings, published in the May 28 issue of TheJournal of the American Medical Association.
"But the study is unable to determine how many men with an elevated PSA level who later returned to normal still could have had prostate cancer -- subsequent 'normal' tests may actually have been false negatives," says Richard M. Hoffman, MD, MPH, of the University of New Mexico School of Medicine.
The PSA blood test, first introduced in the U.S. in 1986, is still a controversial test for prostate cancer. Even though a PSA test is likely to detect prostate cancer at an earlier stage, there is no evidence that the test saves lives. This is because prostate cancer is generally slow-growing and typically strikes men at an older age, when they are more likely to die from other causes. Thus, treating prostate cancer in some men, the argument goes, may cause more harm than benefit.