The prostate-specific antigen (PSA) test is one of the best ways to screen for prostate cancer. This blood test measures a protein made by the prostate that normally is present in the blood. The amount of this protein in the blood will increase in men who have prostate cancer.
The PSA test is reported in nanograms per milliliter (ng/ml).
A PSA count of 0 to 4 ng/ml is considered below normal (and in some men, 1.0 or 2.0) is normal.
A PSA count of 4 to 10 ng/ml is considered slightly elevated.
A PSA count of 10 to 20 ng/ml is considered moderately elevated.
Anything above 20 ng/ml is considered highly elevated.
However, one abnormal PSA test does not necessarily mean that other diagnostic tests must be performed immediately. Factors other than cancer can cause PSA levels to fluctuate. In this case, the doctor may suggest repeating the PSA test a short time later to see if the level returns to normal. When PSA levels continue to rise over time, other tests may be indicated.
Need To Know:
An elevated PSA does not automatically mean a man has prostate cancer. Conditions other than cancer, including an infection or a benign enlargement of the prostate, can result in higher-than-normal PSA levels.
The PSA test is not foolproof.
False positive tests results can occur when the PSA level is elevated, but no cancer is actually present.
False negative test results can occur when the PSA level is in the normal range even though prostate cancer is actully present.
For this reason, experts recommend that the PSA test should be combined with a digital rectal exam for best results.
The American Cancer Society recommends that all men beginning at the age of 50 should have a PSA test every year. Those with prostate cancer in their family should start earlier, at age 45. It is important to have regular tests in order to establish a "baseline," so that any increases in PSA levels can be noted immediately.
Nice To Know:
A Newer PSA Test
Recent studies have shown that a variation of the PSA test, called the percent-free PSA test, may be better at detecting prostate cancer.
The percent-free PSA looks at how much PSA circulates alone (free) in the blood and how much is clinging to other proteins. A low percentage of free PSA, even if the total PSA is not especially high, may mean that prostate cancer is more likely.
The percent-free PSA test is not available at all testing facilities.
Digital Rectal Exam
In a digital rectal exam (DRE), a doctor inserts a gloved, lubricated finger into a man's rectum in order to feel the prostate. If the doctor finds a roughness and irregular uneveness to the tissue, prostate cancer might be suspected. An enlarged prostate that is not cancerous will likely still feel smooth.
The DRE cannot diagnose prostate cancer. It is used to examine the size and surface of the prostate to determine if further investigation is needed. Experts recommend that all men over the age of 50 have a DRE yearly along with a PSA test.
A magnetic resonance imaging (MRI) scan is a computerized picture made by magnetic fields that can show detailed, cross-sectional images of the inner body. MRI scans can create a clear picture of the prostate gland.
Ultrasound uses high-frequency sound waves that bounce off organs and body structures and produce a computerized image. Ultrasound most often is performed by passing a sensor over the surface of the body.
The prostate can be examined through a type of ultrasound called transrectal ultrasonography. In this exam, a tube is inserted into the rectum that carries the sound waves to the nearby prostate, producing a better image.
A CT (computed tomography) scan is a sophisticated x-ray producedure that uses a computer and rotating x-ray beams to produce images of soft tissue, bone, and blood vessels. Areas of dense tissue, such as tumors, can be seen better than with one-dimensional x-rays.
A biopsy is a technique in which a small sample of tissue is taken through a fine needle and examined under a microscope to see if cells are malignant. Biopsy is a highly accurate way to tell if prostate cancer is present.
The way in which the biopsy is performed varies among doctors. Before having a biopsy, a man will want to ask his doctor about:
What the procedure will involve
Whether medication can be given to block any discomfort