9/10/2004 - During national Prostate Cancer Awareness Month, men get extra encouragement to be vigilant about having a regular screening test to be sure that their level of prostate specific antigen, more commonly known as “PSA,” is normal.

But what exactly is “normal?”

Urologist Michael McGuire, MD, explains that it’s important to understand that PSA levels can fluctuate dramatically from day to day – or even hour to hour.   Here, he answers some commonly asked questions about PSA screening – and its limitations

What is a “normal” PSA level?

A PSA ranging from 0 to 4 is considered normal in men. However, PSA values can change from day to day. Many men don’t realize that PSA is released in the blood whenever a prostate cell dies -- and that can happen during normal day-to-day activity, such as when a man has a bowel movement or when he ejaculates. The normal, day-to-day variance in a PSA level can be as high as 20 percent. Also, normal PSA levels vary with age and race. A level of 3.0 is considered elevated in 1 35-year-old man.

So a man shouldn’t necessarily worry if his PSA score is high?

PSAs are often elevated. We know that more than 70 percent of men with an elevated PSA betwen 4 and 10 do not have prostate cancer. Also, 30 percent of men diagnosed with prostate cancer who are being followed by “watchful waiting,” that is, no drugs or treatments, actually see their PSAs go down.

That is why men who are found to have an elevated score should repeat the test. It could be that the man has a benign growth or that it is temporarily elevated for some other reason. Also, keep in mind that a digital rectal exam (DRE) to check for lumps or abnormalities of the prostate is an essential part of a complete prostate cancer screening, because 20 percent of prostate cancers are found in patients with a normal PSA.

When should a man start having his PSA checked, when should he stop?

The American Cancer Society recommends annual PSA testing for all men beginning at age 50, or age 40 for African American men or men who have a family history of prostate cancer. Other groups, including the National Cancer Institute say that the decision to undergo PSA testing should be left up to men and their physicians. Generally, when a man’s life expectancy is 10 years or less, a PSA is no longer appropriate. Prostate cancer often grows slowly in men in the 75-and-older age group.

Why is PSA testing viewed as controversial?

PSA screening detects many slow-growing cancers that may cause few, if any, problems. For some men, the diagnosis and treatment – which may be accompanied by side effects such as incontinence or impotence – may be worse than having the cancer itself. However, it’s important to keep in mind that finding cancer early may prevent you from what can be a very slow and painful death from prostate cancer. Additionally, there is no curative therapy fro prostate cancer once it spreads. Early detection remains our best hope for cure for this potentially lethal disease.  

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