Related topics: •  Prostate Exam •  Prostate Health Center

It helps determine whether you have cancer of the prostate, a walnut-sized gland enfolding the duct leading from the bladder to the penis. The test measures how much of a protein essential to human reproduction, PSA (prostate-specific antigen), is in your blood. The PSA's job is to turn your gelatinous pre-semen into a liquid, thus energizing the sperm.

Your prostate makes this PSA all the time, so a small amount of the protein (usually resulting in a reading of less than 4 ng/mL) is normal. Because cancer cells produce extra PSA, a higher reading may serve as a warning sign. While some experts think there is no specific normal or abnormal level, the higher your PSA, the more likely it is to signal a problem.

Not necessarily. An enlarged or inflamed prostate, which is common in men over age 50, can also give a slight boost to PSA readings. What's more, the test isn't terribly accurate. At least half of all men whose PSA levels are over 4 don't have cancer. And some men with prostate cancer have perfectly normal PSA readings. According to a report in the May 2004 New England Journal of Medicine, 15 percent of a group of 2,950 men with normal PSA levels were found to have prostate cancer.

Fewer men are dying from advanced prostate cancer than in previous years, according to the Centers for Disease Control and Prevention (CDC). Some researchers believe that increased use of testing is responsible for catching prostate cancer in its early stages, when it's more treatable. However, it is still unclear whether the drop in the death rate is a direct result of increased testing. It could be due to other factors, like improved treatments.

Initial studies on the impact of routine screening on mortality rates have shown mixed results. Two large-scale studies are underway to try to clarify whether early screening and detection impacts survival rates. Preliminary results from the Prostate, Lung, Colorectal and Ovarian Cancer Screening Trial, showed that PSA tests and digital rectal exams did not reduce the number of prostate cancer deaths, and may lead instead to unnecessary treatments like surgery and radiation therapy. By contrast, initial results from a large European study found a 20 percent reduction in prostate cancer deaths when PSA testing was done regularly. The final results of these clinical trials will not be known for several more years.

In the meantime, the American Cancer Society does not advise routine screening for prostate cancer for all men. It does recommend that doctors discuss the potential benefits and limitations of testing with their patients, and that they offer the PSA test and a digital rectal exam annually to all male patients beginning at age 50. If you are African American, or have a family history of the disease, that starting age drops to 45.

The US Preventive Services Task Force (USPSTF), the American College of Physicians, the American Society of Internal Medicine, the National Cancer Institute, the Centers for Disease Control and Prevention, the American Academy of Family Physicians, and the American College of Preventive Medicine have concluded that there is insufficient evidence on which to make a recommendation for or against routine screenings for prostate cancer in men age 50 and older. However, for men age 75 and older (and those with a life expectancy of less than ten years), the 2008 USPSTF guidelines recommend against screening for prostate cancer because the risks are likely to outweigh the benefits.

Ultimately, the decision to have the PSA test is a highly personal one and involves many factors. Talk to your doctor about whether it's right for you.

The test is essentially painless. The doctor draws a sample of your blood. The laboratory then mixes it with radioactive PSA-tagging molecules that can be measured easily; the results are available within a few days. If your PSA is below 4, most doctors agree that you needn't be tested again for a year. When you have another test, remember that it's normal for your reading to go up by a few tenths of a point every year. In general, only a drastic increase in PSA (an increase of at least 0.75 points or 20 percent) is considered a reason to worry.

Don't panic: One in three PSA readings between 4 and 10 turns out to signal an actual case of cancer. Your physician will do a few other tests to look for malignancies. You'll get a digital rectal exam, in which the doctor feels for tumors on your prostate. You should also ask for a newer procedure called the free PSA test. It measures how much of your PSA is bound to other proteins in the blood -- if more than 75 or 80 percent is bound, you might have cancer.

If various tests point to cancer, your doctor will probably want to confirm the diagnosis by taking a biopsy, a tiny sample of your prostate tissue, using ultrasound guidance. After the simple outpatient procedure, the sample is examined under a microscope to check for cancer cells.

If cancer cells are detected, you have several treatment options, including surgery and radiation. Because prostate cancer typically grows so slowly, you might also choose an option known as "watchful waiting" -- keeping a close eye on the cancer to see whether treatment is even necessary.

-- Kevin Boyd, formerly a freelance health reporter, now works in the communications department at UCSF Medical School in San Francisco, California.

Further Resources

K. Winston Caine, Peffy Garfinkel and the Editors of Men's Health Books, The Male Body: An Owner's Manual. Rodale Press, 1996.

References

Last updated July 9, 2009
Copyright © 1999 Consumer Health Interactive

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