The long-standing controversy about the value of the prostate-specific antigen (PSA) blood test for the detection of prostate cancer intensified last year when the US Preventive Services Task Force (USPSTF) recommended against it, despite evidence that PSA screening saves lives.
Memorial Sloan-Kettering urologist Peter T. Scardino, Chair of the Department of Surgery, recently coauthored an article with research methodologist Andrew Vickers for the American Urological Association’s AUANews, which suggests taking a balanced approach to prostate-cancer screening and treatment.
We spoke with Dr. Scardino to learn more.
What is the prostate-specific antigen?
PSA is a protein made by cells of the prostate gland. Although it’s normal for men to have low levels of PSA in their blood, prostate cancer can increase a man’s PSA levels. Doctors may recommend a biopsy – the removal of cells or tissue from the prostate gland for examination by a pathologist – for men with an elevated PSA level (greater than or equal to 3 ng/mL) or a rising value over time.
However, an elevated or rising PSA level alone does not always mean that a man has prostate cancer. In fact, most of the time an elevated PSA level also comes with age, and with the onset of other, noncancerous conditions such as benign prostatic hyperplasia, in which the prostate is enlarged, or prostatitis, an inflammation of the prostate gland.
Why has PSA screening been criticized?
The problem is that an elevated PSA test may trigger a biopsy that incidentally finds a low-risk cancer that poses little danger to a man’s health and is very unlikely to become life threatening. Most men with such cancers are treated, even though their cancer is not aggressive and might not cause symptoms during the course of their natural lives. These treatments can lead to long-term health issues that impact quality of life. False-positive test results can also result in an unnecessary biopsy that has its own side effects, such as bleeding or infection.
What are the advantages of using PSA testing to detect prostate cancer?
A number of clinical trials have demonstrated that PSA screening can reduce the risk of prostate cancer death by 20 to 44 percent over ten to 14 years when compared with not screening. If testing substantially decreases, deaths from the disease are likely to rise to the high levels seen prior to the widespread use of PSA screening.
Instead of abandoning PSA testing altogether, we should consider better, smarter ways to use the tool to continue to give patients the benefit of early detection and effective treatment for dangerous prostate cancers, while reducing the risk of harm from overdiagnosis and overtreatment.
How can we strike a balance between the harms and benefits of PSA screening?
We can achieve this balance by using a more-selective and targeted approach to screening. Screening efforts should be focused on men who are at the highest risk of developing a life-threatening prostate cancer. This includes men with a family history of the disease, men with a genetic predisposition to prostate cancer, and African American men.
Older men stand to benefit the least from PSA testing. Research has shown that screening men over age 70 is not likely to be beneficial, but they continue to be screened at high rates.
Memorial Sloan-Kettering’s prostate cancer screening guidelines recommend that men have an initial PSA test at age 45. Based on the results of that test, men at low risk for developing prostate cancer can be tested every five years, but men at an intermediate to high risk should receive more frequent evaluations every two years.
How can doctors further reduce the risk of harm from overtreatment of low-risk prostate cancers?
A diagnosis of prostate cancer requires a biopsy, and men should not have a biopsy without a good reason. In fact, most men with an elevated PSA level do not have prostate cancer. PSA levels vary considerably and should be confirmed with a repeat test in six to 12 weeks before a doctor recommends a biopsy.
In the future, new blood markers now in development such as free-to-total PSA ratios, the 4K score,* and the Prostate Health Index may be able to increase the accuracy of PSA testing in predicting the presence of cancer, especially aggressive disease.
When should prostate cancer be treated?
Prostate cancer treatments such as surgery and radiation therapy can lead to long-term problems with urinary, bowel, and sexual function. At Memorial Sloan-Kettering, we don’t recommend treating prostate cancer unless it is aggressive.
Many cancers detected with PSA screening are at low risk for progressing and do not need immediate treatment. Men found to have a low-risk cancer should consider active surveillance, or watchful waiting, which involves regular monitoring of the cancer for any signs of progression or aggressiveness.
Active surveillance would also be an appropriate option for elderly men with intermediate-risk cancer, as it has been shown that surgery and radiation are usually of little benefit for men over 70, unless a man is unusually fit and otherwise healthy. Such patients should be carefully evaluated, given a repeat biopsy to rule out more-aggressive cancer, and then followed regularly with periodic biopsies.
If treatment for prostate cancer is indicated, studies show that outcomes are better when it is delivered by high-volume practitioners or at high-volume centers such as Memorial Sloan-Kettering, in order to reduce the risk and severity of side effects that may adversely affect a man’s quality of life.
Urologists and primary care physicians who adopt this overall balanced approach and modify the way they counsel their patients about prostate cancer screening and treatment could help countless men in their care.