What is a PSA Level and what does it mean to me

What is PSA

Prostate-specific antigen (PSA) is a protein originally found in semen, the fluid that carries sperm. Normally, PSA is made in cells of the prostate called epithelial cells. Epithelial cells make some of the semen that comes out of the penis at the time of sexual climax (orgasm). PSA helps to keep the semen in its liquid form.

PSA is made only by prostate cells. Small amounts of the protein get into the circulation and can be measured in the blood. Certain prostate conditions, including prostate cancer, can cause high levels of PSA in the blood. PSA itself does not have any known effect outside the prostate; even high levels of PSA are not directly harmful. High PSA levels in the blood, however, may be a sign of a prostate problem, perhaps even a serious one. In addition to prostate problems, some medical treatments can affect PSA levels. The growth of the prostate, as well as the production of PSA itself, is controlled by male hormones. Any treatment that lowers male hormone levels will lead to a drop in PSA blood levels.

How Is PSA Measured?

As with many other routine blood tests, PSA is measured from a small sample of blood. Once a blood sample is taken, the level of PSA in the sample is measured by an accurate laboratory method called an immunoassay. The results are usually reported in ng/ml, shorthand for nanograms per milliliter.

What Is a "Normal" PSA?

There are several different ways to measure PSA. Most physicians think that the "normal range" is between 0 and 4.0 ng/ml for the most common PSA tests. (Because some PSA tests have different normal ranges, you should check with your physician on this point.) The blood level of PSA is often high in men with prostate cancer. However, many men with a PSA level higher than 4 ng/ml do not have prostate cancer or any other important prostate problem. Likewise, a PSA value lower than 4 ng/ml does not rule out the possibility of cancer. The lab's "normal" upper level is simply a cutoff point used to separate men who are less likely to have prostate cancer from those for whom further prostate cancer testing may be appropriate, depending upon the circumstances.

What Causes PSA to Rise?

The level of PSA in the bloodstream may be elevated by an process that leads to an increase in the number of cells making PSA or to a breakdown of the normal barriers in the prostate that prevent much PSA from getting into the bloodstream. The most common condition leading to a high PSA is benign (noncancerous) enlargement of the prostate, called benign prostatic hyperplasia (BPH). BPH is very common in men over the age of 50 and may lead to difficulty with urination. Infection or inflammation in the prostate, called prostatitis, may also cause elevation of PSA by damaging the PSA barrier in the prostate. In addition, some diagnostic tests, such as a needle biopsy of the prostate, may increase PSA levels for several weeks. It does not appear that a routine digital rectal examination (DRE) of the prostate by the doctor's finger causes an elevation of the PSA.

Both BPH and prostate cancer are common in men over the age of 50. In addition, there is a lot of overlap in blood PSA levels between men with BPH and those with early prostate cancer. These factors limit the usefulness of PSA as a tool for detecting curable prostate cancer. Many patients who have a PSA level higher than 4 ng/ml will eventually be found not to have prostate cancer. These men have a "false-positive" test. If PSA is tested on men with BPH but no prostate cancer, as many as one-third to one-half of such men will have an elevated PSA. Their PSA results, however, are generally in the 4 to 10 ng/ml range

In addition to false-positive tests, the PSA may be falsely negative -- that is, normal even when prostate cancer is present. Some 30 to 40 percent of patients with early-stage prostate cancer have a normal PSA. Repeating PSA tests once every year may be useful to find some of the cancers in men who have a normal PSA at first.

False-negative and false-positive findings limit the value of PSA testing. Despite this, PSA testing has led to an increase in the detection of prostate cancer

PSA Testing Finds Men Who May Need More Tests

Prostate cancer is not actually diagnosed by PSA or digital rectal examination (DRE). PSA and DRE help to find men at higher risk for prostate cancer -- men on whom a biopsy may be indicated. Only with a biopsy can the diagnosis be made. A biopsy of the prostate involves taking a sample of tissue by inserting a small needle through the rectum into the prostate gland. Often four to six biopsies are taken at a time. The tissue samples are then examined by a pathologist who looks for cancer cells

What Is the Value of Early Prostate Cancer Detecting?

Most cancers have a better chance of cure if found and treated during an early stage, before the cancer has had a chance to spread to other parts of the body. Many prostate cancer patients who have been treated with surgery or radiation therapy never again have problems with their cancer. On the other hand, some men with prostate cancer will not die of the disease even if it remains untreated. Thus, it is not possible to say whether early detection of prostate cancer will lower an individual patients' chance of eventually dying from that cancer. Although early detection makes sense, there are certain types of cancers, such as lung cancer, for which screening programs have not been found to reduce death rates.

Prostate cancer is the second most common cause of cancer death in men. Although many men with advanced prostate cancer die from this disease, others with small amounts of prostate cancer die from other causes, for example, heart disease. Clearly, not all men with prostate cancer need treatment. At this time, unfortunately, doctors cannot be certain which cancers need treatment and which do not. Until these issues are settled, the true value of PSA testing cannot be determined.

Should I Have a PSA Test?

Before deciding whether to have a PSA test, you need to decide whether you would be willing to undergo treatment for prostate cancer. Should you decide that the benefits of treatment outweigh the complications of therapy, then a PSA test would be wise. Because physicians themselves do not agree on the value of the test, this should be a personal decision on your part. The American Cancer Society, for example, has recommended a PSA test every year in men over the age of 50, or men over 40 with blood relatives who have had prostate cancer, or men who are in high-risk groups, such as African Americans. Other expert groups believe that there is not enough evidence to make such recommendations. Even advocates of PSA testing seriously question the value of routine PSA testing in elderly men whose life expectancy is less then 10 years.

What Do My PSA Results Mean?

If your DRE is normal and your PSA blood level is less than 4 ng/ml (on the most common tests), no further testing usually is needed at this time. Physicians who recommend PSA testing generally suggest that you should have both the DRE and PSA each year. If your PSA is over 4 ng/ml or your rectal exam shows an area of hardness or firmness in your prostate, most experts would recommend that you have a prostate biopsy.

About one in 20 healthy men who are screened will have prostate cancer detected. If either the PSA or DRE is abnormal, your risk of having prostate cancer increases. Although there is some uncertainty, your overall risk of prostate cancer, based upon the PSA and DRE results.

Conclusion

Many factors can use PSA to rise, but PSA itself is harmless. The yearly PSA blood test is used, with digital rectal examination (DRE), to find men who may have prostate cancer and who need further testing. PSA cannot diagnose prostate cancer, however, only a biopsy can do that. The PSA test is also used to track the progress of men being treated for prostate cancer. If treatment is effective, the PSA should remain low. Improved methods of PSA testing are being developed. In the future, these may help your urologist to decide whether a rise in PSA is due to prostate cancer or to a less serious problem

The preceding information was taken from excerpts from "The American Foundation for Urologic Disease. for additional information please visit their site at AFUD.