Harvard Medical School
Healthbeat
April 13, 2010
The pros and cons of PSA screening
A prostate-specific antigen (PSA) blood test measures the level of a protein called prostate-specific antigen (PSA), which is made by cells in the prostate. Doctors use the test to detect prostate cancer. Since its introduction in the late 1980s, the prostate-specific antigen (PSA) test has been hailed as a way to detect prostate cancer in its earliest, most curable stage. It has been called one of the most important tests a man can have. So why are many experts now stepping back, and even discouraging the use of widespread PSA screening?
Concerns about PSA screening
The shift comes on the heels of a growing body of evidence that shows the benefits of PSA screening may not outweigh the potential harm of unnecessary treatment. PSA screening has always been somewhat controversial. That?s because PSA tests often alert doctors to the presence of cancer, but there is no precise way to determine, definitively, whether the cancers detected would have ever caused symptoms or harm during a man?s lifetime. One study estimated overdetection to rise with age, from 27% at age 55 to 56% by age 75.
Despite this, to be on the safe side, most men with elevated PSA levels will opt for treatment, frequently suffering side effects such as incontinence and impotence. Increasingly, there are questions about the effectiveness of PSA screening for prostate cancer. Just how many lives are actually being saved? And is the emotional and physical toll on the millions of men who are being overdiagnosed and overtreated worth it?
What the research says
Two long-awaited studies?one conducted in the United States and the other in Europe?were supposed to help settle the debate over the value of PSA testing. Instead, the trials, published in the New England Journal of Medicine in March 2009, seemed to come to opposite conclusions. The Prostate, Lung, Colorectal, and Ovarian (PLCO) Cancer Screening Trial reported no survival benefit with PSA screening and digital rectal examination, but the European Randomized Study of Screening for Prostate Cancer (ERSPC) found a 20% reduction in prostate cancer deaths. The ERSPC study estimated that for every life saved, 48 men are treated and 1,068 men are screened.
Although experts are somewhat split on the value of PSA tests as a screening tool, there is widespread agreement on two major points: overdiagnosis and overtreatment rates are far too high, and there is an urgent need to refine PSA testing to be a more effective screening tool. The principal investigator of the Prostate Cancer Prevention Trial and his colleagues wrote an editorial in The Journal of the American Medical Association in October 2009 that took a closer look at the issues. They pointed out that while the amount of prostate cancer diagnosed has risen dramatically since PSA testing began, there has not been a proportional decrease in the number of men with metastatic tumors. It appears screening may be detecting a disproportionate number of lower-risk cancers, while missing many of the most aggressive tumors, which may advance too rapidly to be found with periodic testing.
The debate over the effectiveness of PSA screening has quickly filtered into the offices of general practitioners and urologists. On a daily basis, confused men are asking their doctors: ?Should I have a PSA test or not??
What you should know about PSA screening
PSA testing guidelines from the American Cancer Society emphasize discussing the pros and cons of prostate cancer screening with your doctor, including your individual level of prostate cancer risk, before having a PSA blood test
Healthbeat
April 13, 2010
The pros and cons of PSA screening
A prostate-specific antigen (PSA) blood test measures the level of a protein called prostate-specific antigen (PSA), which is made by cells in the prostate. Doctors use the test to detect prostate cancer. Since its introduction in the late 1980s, the prostate-specific antigen (PSA) test has been hailed as a way to detect prostate cancer in its earliest, most curable stage. It has been called one of the most important tests a man can have. So why are many experts now stepping back, and even discouraging the use of widespread PSA screening?
Concerns about PSA screening
The shift comes on the heels of a growing body of evidence that shows the benefits of PSA screening may not outweigh the potential harm of unnecessary treatment. PSA screening has always been somewhat controversial. That?s because PSA tests often alert doctors to the presence of cancer, but there is no precise way to determine, definitively, whether the cancers detected would have ever caused symptoms or harm during a man?s lifetime. One study estimated overdetection to rise with age, from 27% at age 55 to 56% by age 75.
Despite this, to be on the safe side, most men with elevated PSA levels will opt for treatment, frequently suffering side effects such as incontinence and impotence. Increasingly, there are questions about the effectiveness of PSA screening for prostate cancer. Just how many lives are actually being saved? And is the emotional and physical toll on the millions of men who are being overdiagnosed and overtreated worth it?
What the research says
Two long-awaited studies?one conducted in the United States and the other in Europe?were supposed to help settle the debate over the value of PSA testing. Instead, the trials, published in the New England Journal of Medicine in March 2009, seemed to come to opposite conclusions. The Prostate, Lung, Colorectal, and Ovarian (PLCO) Cancer Screening Trial reported no survival benefit with PSA screening and digital rectal examination, but the European Randomized Study of Screening for Prostate Cancer (ERSPC) found a 20% reduction in prostate cancer deaths. The ERSPC study estimated that for every life saved, 48 men are treated and 1,068 men are screened.
Although experts are somewhat split on the value of PSA tests as a screening tool, there is widespread agreement on two major points: overdiagnosis and overtreatment rates are far too high, and there is an urgent need to refine PSA testing to be a more effective screening tool. The principal investigator of the Prostate Cancer Prevention Trial and his colleagues wrote an editorial in The Journal of the American Medical Association in October 2009 that took a closer look at the issues. They pointed out that while the amount of prostate cancer diagnosed has risen dramatically since PSA testing began, there has not been a proportional decrease in the number of men with metastatic tumors. It appears screening may be detecting a disproportionate number of lower-risk cancers, while missing many of the most aggressive tumors, which may advance too rapidly to be found with periodic testing.
The debate over the effectiveness of PSA screening has quickly filtered into the offices of general practitioners and urologists. On a daily basis, confused men are asking their doctors: ?Should I have a PSA test or not??
What you should know about PSA screening
- Screening doesn?t lower your risk of having prostate cancer; it increases the chance you?ll find out you have it.
- PSA testing can detect early-stage cancers that a digital rectal examination (DRE) would miss.
- A ?normal? PSA level of 4 ng/ml or below doesn?t guarantee that you are cancer-free; in about 15% of men with a PSA below 4 ng/ml, a biopsy will reveal prostate cancer.
- A high PSA level may prompt you to seek treatment, resulting in possible urinary and sexual side effects.
- Conditions other than cancer?BPH and prostatitis, for example?can elevate your PSA level.
PSA testing guidelines from the American Cancer Society emphasize discussing the pros and cons of prostate cancer screening with your doctor, including your individual level of prostate cancer risk, before having a PSA blood test
