The following is an excerpt from the Mayo Clinic Press book Mayo Clinic on Prostate Health, 3rd Edition by Derek J. Lomas, M.D. and Paras H. Shah, M.D.
The PSA test was approved by the Food and Drug Administration in 1986 as a means to help detect prostate cancer.
Since that time, including the test in standard physical exams has resulted in a significant increase in the recorded number of cases of prostate cancer. But controversy still remains concerning the dependability and utility of PSA test results.
The test begins with a small amount of blood drawn from your arm that’s sent to a laboratory, where a specialized procedure called an immunochemical assay determines how much of the prostatespecific antigen is circulating in your bloodstream.
A reading between 0 and 4 nanograms per milliliter (ng/mL) is generally considered to be standard, or typical. However, because PSA levels tend to naturally increase as you get older, some medical centers have adjusted their standards based on age.
Just because your PSA level is below the upper limit of normal doesn’t rule out the presence of prostate cancer. Similarly, just because your PSA is elevated doesn’t necessarily mean you have cancer. Some men have higher-than-normal PSA levels and healthy prostates.
It’s also important to understand that other conditions or actions in addition to cancer can increase the amount of PSA in your bloodstream:
• BPH. Noncancerous enlargement of the prostate is the most common condition that can cause an elevated PSA reading. As prostate tissue grows, cells within the tissue produce more PSA — sometimes up to three times higher than is typical.
• Prostatitis. Irritation of the prostate gland due to inflammation or infection can cause cells to release or leak higher amounts of PSA into the bloodstream.
• Urinary tract infection. Similar to an infection in your prostate gland (prostatitis), a urinary tract infection can increase the PSA level in your blood.
• Ejaculation. The release of semen can cause a temporary increase in PSA levels. For that reason, some doctors have advised patients to abstain from sexual activity for up to 2 days before having their PSA exam.
In addition, procedures used to treat BPH (discussed in Chapter 5) can temporarily irritate the prostate gland, producing abnormal levels of PSA. These procedures include:
• Prostate biopsy.
• Transurethral resection of the prostate.
• Transurethral incision of the prostate.
• Microwave therapy of the prostate.
• Laser therapy of the prostate.
Following one of these procedures, you should wait 2 weeks to 2 months before having a PSA test.
The PSA test is able to identify early-stage prostate cancer about 75% of the time. In about 25% of men with early-stage prostate cancer, PSA results come back within the standard range (less than 4 ng/
mL). This is a major drawback of the test. If a PSA test is the only screening tool, early-stage prostate cancer in about 1 of 4 men will go undetected.
As mentioned earlier, another drawback of using PSA as a screening tool is that the results don’t distinguish between cancer and other prostate diseases. Among men with elevated PSA levels who undergo a biopsy, 75% don’t have cancer. Increased PSA levels in these men may be a result of BPH, prostatitis or other factors.
As a result, many men who don’t have cancer undergo testing that’s expensive, time-consuming and may be hard on their physical and emotional health.
Because of these drawbacks, not all doctors and medical organizations agree that the benefits of the PSA test outweigh its limitations. That’s why this simple test remains controversial.
The benefit of regular PSA screening is that it can help identify prostate cancer long before any signs or symptoms become apparent — often when the cancer is still confined to the prostate gland. Localized cancer is much easier to treat and cure than cancer that’s spread to other organs and tissues in the body.
Not all prostate cancers are alike. Some cancers grow slowly and remain within the prostate gland. Others are more aggressive and spread rather quickly to other organs. If your PSA test detects what turns out to be an aggressive form of prostate cancer, it could be a lifesaver.
The year 1995 marked the first-ever reduction in deaths from prostate cancer. Many doctors believe, and some studies support, that the PSA test was a major factor behind this decrease. However, health experts haven’t been able to prove this link with certainty.
Among men for whom test results come back normal, the results may provide a false sense of security. And among men with an elevated PSA, the men may go through needless worry and unnecessary, expensive diagnostic procedures to learn they don’t have cancer.
Whether the test leads to needless treatment is another question. If you have a slow-growing cancer, you may be able to monitor your condition and live with the cancer for years without it causing any problems.
Some men, however, find the waiting game difficult to accept. When they learn they have cancer, they want to do everything they can to get rid of it, opting for treatments such as surgery or radiation therapy. These treatments may lead to side effects, including incontinence or impotence. These conditions can decrease the quality of life for men who might otherwise have enjoyed perfectly healthy, productive lives.
Finally, the issue of whether the early detection and treatment of prostate cancer actually saves lives remains unresolved. A large European study (European Randomized Study of Screening for Prostate Cancer, or ERSPC) comparing men who underwent PSA screening to those who didn’t showed a significant reduction in prostate cancer deaths and risk for cancer spread (metastasis) among men who had PSA screening.
But another study conducted in the United States (Prostate, Lung, Colorectal and Ovarian Cancer Screening Trial, or PLCO) indicated there was no benefit in overall or cancer-specific survival with PSA screening. Specifically, trial data found that men who underwent annual prostate cancer screening (with PSA testing and a digital rectal exam) had a 12% higher incidence of prostate cancer than did men who didn’t undergo routine screening exams. However, after 13 years of follow-up, researchers didn’t find a statistically significant difference in mortality rates between the two groups.
A caveat: While the control group in the PLCO trial didn’t receive annual screening through the trial, the majority were screened at least once during the trial as part of their regular care. So, while the trial results found no survival benefit with annual screening as compared with opportunistic screening, there was no comparison of regular screening versus no screening as in the ERSPC trial.
Mayo Clinic on Prostate Health, 3rd Edition
Mayo Clinic on Prostate Health, 3rd Edition is an easy-to-read yet comprehensive guide to preventing, understanding, treating and living with prostate disease. Advances in research, an explosion in sophisticated imaging technology and new medical procedures have allowed for earlier diagnosis of prostate disease and more personalized treatment.Shop Now