Should You Get a PSA Test?
Walter Petersen gets a digital rectal exam and a prostate-specific antigen (PSA) test for prostate cancer as part of his yearly physical. For 10 years, he scored a 2 on the PSA test, which is normal. But, his PSA level shot up to 4.2. Three months later, it was 6.2. Time for a biopsy, his doctor told him. The biopsy showed prostate cancer. Today, after undergoing radioactive seed implant treatment, Petersen is cancer-free.
"My digital rectal exam was normal and I had no symptoms," says Petersen. "If it wasn't for the PSA test, no one would have known I had cancer."
Stories like this make it hard to understand why doctors disagree about how useful the prostate-specific antigen test really is. Some doctors believe it detects prostate cancer early enough to reduce deaths and prolong life. Others say there's no proof it does either. Even authoritative bodies like the US Preventive Services Task Force and the American Cancer Society don’t see eye-to-eye on the PSA test.
What Is the PSA Test?
The PSA test is a simpleblood test that measures the levels of prostate-specific antigen in your blood. It's usually done during a routine physical. All prostates—healthy and unhealthy—produce PSA, so it's normal to have some PSA in your blood. And it's normal for that level to rise as you get older. But PSA levels that rise too high or too fast may indicate prostate cancer.
Readings of 0-4 are considered normal unless the level is rising rapidly. Some scientists believe that a level above 2.0 ng/ml is of concern in men with a family history of prostate cancer, or in men younger than age 60. Others believe a PSA level above 1.0 ng/ml in men younger than age 40 is also of some concern. As men age, so does the secretion of prostate-specific antigen, and therefore a level of 4-5 in men over age 70 is generally acceptable. Much higher than a value of 7 is reason for concern. Many scientists will do other tests to clarify an elevated PSA test.
What Do the Results Mean?
A high blood PSA level may mean you have prostate cancer. But, you may not. This is one problem with the test. It measures high levels of PSA in your blood, but does not tell you why it's high. You may have a prostate infection ( prostatitis ) or a noncancerous enlargement of the prostate (called benign prostatic hyperplasia). Levels also go up temporarily after sex, or after having a digital rectal exam.
Only 15%-20% of men with high PSA levels have prostate cancer. The cancer rate is higher (40% or greater) among men with PSAs greater than 10. But, that means a lot of men with high PSA levels don't have cancer. In other words, the test produces a lot of what doctors call "false-positives," results that falsely indicate prostate cancer.
The test also produces many "false-negatives," meaning some men with normal PSA levels may have prostate cancer. Most prostate cancers are slow-growing. The cancer may exist for decades before it is large enough to cause symptoms. Later PSA tests may show that there is a problem before the cancer progresses.
What Is the Right Choice for You?
Say you have a PSA test and your levels are high. What should you do next?
You could repeat the test to see if the value is rising. Under the right conditions, it can be the best choice for many men. For example, Petersen waited three months. But, especially if you are younger, you'll proceed to the next level and get a biopsy of your prostate.
If the biopsy is negative, that's good news. But, a biopsy can miss cancer if the sample came from a noncancerous part of your prostate. So a second biopsy may be needed. A second negative negative result may be good news. Although, this too can mean that the cancerous cells are hard to find.
What if the biopsy's positive? If the cancer is aggressive, it should be treated, unless you're very old. If it's not aggressive, your quality of life may be better if the cancer is left untreated. It's impossible for doctors to predict which cancers will turn into life-threatening problems. Most do not. They just continue to grow slowly without significant problems.
What Are the Problems With Treatment?
Some studies state that many men would do better not to treat early prostate cancer. This is because the side effects of treatment can be worse than the disease.
A study published in the Journal of Clinical Oncology reported that after prostate removal:
- 8% had problems with urinary control (compared to 10% who had radiation therapy)
- 3% had bowel problems (compared to 7% who had radiation therapy)
- 50% had sexual function problems (compared to 46% who had radiation therapy)
Newer techniques result in somewhat better outcomes. According to a study, as many as 67% of men may recover the ability to achieve erections after six months.
Even external beam radiation poses a significant risk of impotence. There is also a 10% chance for permanent bowel problems. New techniques, though, may reduce these risks.
Is the Screening Helpful?
Nationwide, 60% of all prostate cancers are now discovered before they spread outside the gland.
"The test allows us to detect a cancer on average five years earlier," says Michael Blute, MD, a urologist at the Mayo Clinic in Rochester, Minnesota. "That translates into a better chance the cancer can be effectively treated."
The Mayo Clinic strongly believes in the PSA test and has the research to support that opinion, according to Dr. Blute. Their research shows that among men in their 50s and 60s living in Olmstead County, Minnesota, "incidence of late-stage prostate cancer has decreased since the mid-1990s when the PSA test caught on," says Dr. Blute. "We've also seen an overall decrease in the incidence of prostate cancer. And now, most importantly, we've seen a reduction in death rates."
James Talcott, MD, from Massachusetts General Hospital Cancer Center, is not so sure the decline in death rates is due to the PSA test. "It's possible," he says, "that the improved statistics may be due to other factors like changes in men's diets and how data are collected."
Is the Screening More Popular Now?
Despite disagreement among the medical community, conventional medical wisdom increasingly favors using the test, even for men who have no symptoms or family history. According to Jeff Engelsgjerd, MD, a urologist at St. Mary's/Duluth Clinic, the PSA test is, for now, the best way to detect early stage prostate cancer.
"It's not a perfect test," he says, "but for now, it's the best thing we have." Dr. Engelsgjerd recommends that all his patients over age 50, regardless of risk factors, have a yearly PSA test and digital rectal exam.
The American Urological Association (AUA) agrees that PSA tests are at least partially responsible for the dramatic increase in detecting prostate cancer and finding the cancer before it spreads. The AUA also recommends that the test be used along with digital rectal exams.
As a last thought, consider why screening tests are used. The test must be reliable and allow doctors to diagnose a disease that can be treated effectively. In treating the disease, the doctor must prove that detecting the disease at an earlier stage will result in a better outcome than if the disease was found at a later, more advanced stage. Early stage prostate cancer is very unlikely to kill a patient, while more a advanced stage is far more likely be a cause of death.
Ultimately, having the test is your decision. Talk with your doctor to make the best choice for you.
American Urological Association
Canadian Cancer Society
Canadian Prostate Cancer Network
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Last reviewed June 2008 by Adrienne Carmack, MD
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