Prostate-specific antigen (PSA) test
The Prostate-specific antigen (PSA) test is a blood test used primarily to screen for prostate cancer. PSA is a protein produced by both normal and cancerous prostate cells, and elevated levels may suggest the presence of prostate cancer or other noncancerous conditions, such as benign prostatic hyperplasia (BPH) or prostatitis. The test is typically administered to establish a baseline PSA level, which is then monitored annually for changes. While the PSA test can detect early signs of prostate cancer, its utility has been debated due to the potential risks and limited benefits associated with its use.
Prostate cancer is notably prevalent among men in the United States, with a significant number of diagnoses and deaths annually. Certain demographics, including older men and those with a family history of the disease, are at higher risk. Recommendations for screening have evolved, with some guidelines suggesting that only high-risk individuals undergo testing before age 45, while routine screening is urged for men aged 55 to 69.
The test procedure is straightforward, requiring no special preparation, and results typically take a few days to a couple of weeks. However, false positives or negatives can occur, necessitating follow-up tests like ultrasounds or biopsies if PSA levels are elevated. Recent advancements in PSA testing, including additional blood tests and at-home testing options, have aimed to enhance accuracy and accessibility for men considering prostate cancer screening.
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Prostate-specific antigen (PSA) test
ALSO KNOWN AS: PSA blood test
DEFINITION: The protein-specific antigen (PSA) test is a simple blood test used to screen for prostate cancer. PSA is a protein produced by both normal and cancerous prostate cells that is released into the blood. High levels of PSA may be indicative of prostate cancer, as well as other noncancerous conditions such as benign prostatic hyperplasia (BPH) or an infection or inflammation in the prostate. The first PSA test determines the baseline level. The PSA levels are compared each year and monitored for any changes. Opinions on whether men should undergo the PSA test have dramatically changed, largely because of the high risk and relatively minor benefits associated with the test. Men should consult with their physician to understand the risks before undergoing the test.
Cancers diagnosed:Prostate cancer
Why performed: The benefit of this test is that it can detect signs of early-stage prostate cancer when there are no symptoms. When this cancer is treated in the early stages of the disease, there is a high probability of cure.
Prostate cancer is the most common form of cancer among men in the United States (the other common male cancers are lung and colorectal cancers) and the second leading cause of death behind heart disease. The American Cancer Society estimated that nearly 299,010 men in the United States would be diagnosed with this disease in 2024, and more than 35,250 men would die from it.
Certain groups of men are at a greater risk of developing prostate cancer. Age is a risk factor; the older a man gets, the higher the risk of getting prostate cancer. More than 60 percent of all diagnosed prostate cancer is found in men sixty-five years of age or older. Men with a family history of prostate cancer in an immediate relative, such as a father, brother, or son, are two to three times more likely to develop the disease. It is also more common among Black American men, with more men in this racial group dying from the disease than in any other ethnic group. It is less common in men who are Hispanic, Asian, Indigenous American, or from the Pacific Islands.
In the past, men at high risk for the disease were advised to begin testing with a digital rectal examination (DRE) and a PSA test at age forty-five, while all men fifty years and older were advised to be screened. However, medical professionals disagree on the PSA test. The American Urological Association suggests that only high-risk cases undergo the PSA test under the age of forty-five. For men who have had prostate cancer, the test should be repeated yearly unless a medical provider suggests otherwise. Men between the ages of fifty-five and sixty-nine are recommended to get the test. However, the PSA test is not recommended for men over seventy.
Patient preparation: No special preparation is needed for this blood test. However, there are indications that a recent urinary tract infection, a recent urinary catheter, prostate stones, a prostate massage, or a DRE right before the blood test may cause the PSA levels to rise. Therefore, it is recommended to avoid those situations before the blood test to avoid a false rise in PSA.
Steps of the procedure: Since this procedure is a blood test, it takes only a few minutes to perform. The blood is then sent to a laboratory for analysis. It may take a few days up to two weeks before the test results are available.
After the procedure: The patient can return to normal activity. It is important to follow up on the results of the blood test to ensure that the PSA levels are within normal limits.
Risks: False positive or false negative results; resulting procedures that may negatively affect other body parts.
Results: There are several ways to interpret PSA results. A more traditional approach considers less than 4 nanograms per milliliter (ng/mL) normal, 4 to 10 ng/mL slightly elevated, 10 to 20 ng/mL moderately elevated, and over 20 ng/mL significantly elevated. Other physicians evaluate the PSA level based on age and suggest that the normal ranges vary by age group. For physicians who take that approach, less than 2.5 ng/mL is normal for men forty to forty-nine years old, less than 3.5 ng/ml is normal for men fifty to fifty-nine years old, less than 4.5 ng/mL is normal for men sixty to sixty-nine years of age. Less than 6.5 ng/mL is normal for men seventy or older.
If the initial PSA level is within normal limits, then one of the most important factors in determining whether prostate cancer is present is the change in PSA level from year to year. A dramatic rise in PSA levels from one screening to the next may be indicative of the presence of prostate cancer or other problems with the prostate. When the PSA level is elevated, it is important to have additional testing to determine the cause. Additional tests may include a transrectal ultrasound, in which a small probe is inserted into the rectum to take video images of the prostate, or a biopsy of the prostate, which involves inserting a needle into the prostate to take tissue samples. These samples are then checked for evidence of cancer.
Several advances in prostate-specific antigen testing have occurred, allowing for increased accuracy and efficiency. For men with a PSA between four and ten, the United States Food and Drug Administration has approved a blood test called the Prostate Health Index, which combines other forms of PSA testing. Similarly, the 4Kscore test, the Prostate Screening EpiSwitch blood test, and urine tests also offer increased accuracy. Finally, at-home blood testing has allowed men to capture blood at home and send it to a laboratory for testing, increasing convenience and the likelihood that men will be screened for prostate cancer.
Bibliography
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Ellsworth, Pamela, John Heaney, and Cliff Gill. One Hundred Questions and Answers about Prostate Cancer. Sudbury: Jones, 2003.
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