The lower the PSA threshold for prostate biopsies and the more cores of tissue taken with each biopsy, the greater the risk of overdiagnosis. Hundreds upon hundreds of scientific papers have been written about the pros and cons of PSA screening, and debate in the public arena has often seemed even more intense than in the medical community.
Until now, medical experts have divided into two broad camps, which we might call the PSAdvocates and the PSAgnostics. Here's the gist of their positions. The American Cancer Society ACS recommends that doctors discuss annual PSA testing with every man above the age of 50 who has a life expectancy of 10 years or longer; it also calls for yearly discussions to start at the age of 45 for men at increased risk, including African Americans and men with family histories of prostate cancer.
The ACS says that if a man cannot decide, his doctor should recommend testing. Until , they had the same guidelines as the ACS, but their guidelines now call for doctors to offer the test to all men with a life expectancy of at least 10 years, beginning at age They have a point. Requiring only a single blood sample, PSA testing is quick, easy, and safe. Early detection is surely the best hope for curing prostate cancer, and PSA screening is the best way to find early disease. The U.
Preventive Services Task Force recommends against testing for men age 75 or older as well as for men with life expectancies of 10 years or less. For other men, the task force notes that the "potential harms of screening for prostate cancer can be established, [but] the presence or magnitude of potential benefits cannot. They, too, have a point. Still, it might save money if early diagnosis could reduce the need for even more expensive treatment of advanced cancer. But critics go beyond economics to consider the problem of overdiagnosis.
The PSAgnostics have long argued that screening might produce more harm than good if it leads to unnecessary treatment in men who would never be harmed by their prostate cancers. For all their differences, the PSAdvocates and PSAgnostics have agreed on one point: the only way to resolve the issue is with high-quality randomized clinical trials.
And that's just why the two studies are so important. Over the next eight years, 76, men between the ages of 55 and 74 volunteered for the study, which was conducted at 10 medical centers around the United States. Scientists randomly assigned half the men to receive annual PSA testing for six years along with annual digital rectal exams DREs for four years; men who had PSA levels above 4.
Men in the comparison group continued to receive their usual medical care. Men in either group who were diagnosed with prostate cancer were treated by their personal physicians; PLCO researchers monitored the treatment methods and found they were similar in the two groups. The PLCO scientists tracked the men to find out how many were diagnosed with prostate cancer and how many died from the disease. However, even though PSA screening increased the diagnosis of prostate cancer, it did not improve survival.
About two-thirds of the men have completed another three years of follow-up in this ongoing study; the results at 10 years mirror the findings at seven years. The PLCO study is slated to continue until all the volunteers have been evaluated for 13 years. Researchers are compiling information on treatment side effects and quality of life along with additional mortality data.
A total of , men between the ages of 55 and 69 volunteered for the study. Scientists randomly assigned half the men to receive PSA screening and the other half to receive their usual medical care. Because the study was conducted in multiple medical centers spread across seven countries, the investigators followed a number of slightly different research protocols.
In most cases, PSA screening was performed an average of once every four years and, in most study centers, readings of 3. Men who were diagnosed with prostate cancer were treated by their own physicians according to local guidelines. After about nine years of observation, men in the PSA screening group had died from prostate cancer, while men in the comparison group had died from the disease.
But the reduced mortality came at a price: an additional 48 men who were not destined to die from prostate cancer had to be treated to prevent one death from the disease. The ERSPC scientists will continue to monitor the volunteers, evaluating both deaths from prostate cancer and side effects of treatment and quality of life.
Neither study provides information beyond 10 years, but both are ongoing, which is important because many prostate cancers grow very slowly. Still, the differences in screening rates are large enough that if testing produced a benefit, it should show up in a study this big. Some experts are likely to assert that the PSA cutoff of 4. The American study found that PSA screening did not prevent death from prostate cancer during the first decade of screening. The European investigators reported a small mortality benefit, but at substantial cost of overdiagnosis and overtreatment.
They found that a man whose prostate cancer was diagnosed by screening would have a one-in chance of gaining a lifesaving benefit from prostate cancer treatment. Limitations in the studies ensure that a healthy discussion will continue, and we are all looking forward to results from additional research, such as PIVOT Prostate Cancer Intervention Versus Observation Trial in the U.
But in science, as in politics, the perfect should not become the enemy of the good. Attention must be paid. If prostate cancer is suspected, the doctor will recommend a prostate biopsy. During this procedure, multiple samples of prostate tissue are collected by inserting hollow needles into the prostate and then withdrawing them.
Most often, the needles are inserted through the wall of the rectum transrectal biopsy. A pathologist then examines the collected tissue under a microscope. The doctor may use ultrasound to view the prostate during the biopsy, but ultrasound cannot be used alone to diagnose prostate cancer. Detecting prostate cancer early may not reduce the chance of dying from prostate cancer.
When used in screening, the PSA test can help detect small tumors that do not cause symptoms. Overtreatment exposes men unnecessarily to the potential complications and harmful side effects of treatments for early prostate cancer, including surgery and radiation therapy. The side effects of these treatments include urinary incontinence inability to control urine flow , problems with bowel function , erectile dysfunction loss of erections , or having erections that are inadequate for sexual intercourse , and infection.
In addition, finding cancer early may not help a man who has a fast-growing or aggressive tumor that may have spread to other parts of the body before being detected. The PSA test may give false-positive or false-negative results. A false-positive test result may create anxiety for a man and his family and lead to additional medical procedures, such as a prostate biopsy, that can be harmful. Possible side effects of biopsies include serious infections, pain, and bleeding.
False-negative test results may give a man, his family, and his doctor false assurance that he does not have cancer, when he may in fact have a cancer that requires treatment. Several randomized clinical trials of prostate cancer screening have been carried out.
The PLCO investigators found that men who underwent annual prostate cancer screening had a higher incidence of prostate cancer than men in the control group but the same rate of deaths from the disease 3. Overall, the results suggest that many men were treated for prostate cancers that would not have been detected in their lifetime without screening. Consequently, these men were exposed unnecessarily to the potential harms of treatment. In contrast to the PLCO, however, men who were screened had a lower rate of death from prostate cancer 4 , 5.
A recent paper analyzed data from the PLCO using a complicated statistical model to account for the fact that some men in the PLCO trial who were assigned to the control group had nevertheless undergone PSA screening. This analysis suggested that the level of benefit in the PLCO and ERSPC trials were similar and that both trials were consistent with some reduction in prostate cancer death in association with prostate cancer screening 6.
Such statistical modeling studies have important limitations and rely on unverified assumptions that can render their findings questionable or more suitable for further study than to serve as a basis for screening guidelines. More importantly, the model could not provide an assessment of the balance of benefits versus harms from screening.
The United States Preventive Services Task Force has analyzed the data from all reported prostate cancer screening trials, principally from the PLCO and ERSPC trials, and estimated that, for every 1, men ages 55 to 69 years who are screened every 1 to 4 years for 10 to 15 years 7 :. The PSA test is often used to monitor patients who have a history of prostate cancer to see if their cancer has recurred come back.
However, a single elevated PSA measurement in a patient who has a history of prostate cancer does not always mean that the cancer has come back. A man who has been treated for prostate cancer should discuss an elevated PSA level with his doctor. The doctor may recommend repeating the PSA test or performing other tests to check for evidence of a recurrence.
Scientists are investigating ways to improve the PSA test to give doctors the ability to better distinguish cancerous from benign conditions and slow-growing cancers from fast-growing, potentially lethal cancers.
None has been proven to decrease the risk of death from prostate cancer. Some of the methods being studied include:. Menu Contact Dictionary Search. Understanding Cancer.
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PSA is also widely used to monitor responses to therapy and is under investigation as a therapeutic target. Abstract Prostate-specific antigen PSA is an androgen-regulated serine protease produced by both prostate epithelial cells and prostate cancer PCa and is the most commonly used serum marker for cancer. Publication types Research Support, Non-U. The PSA test can detect high levels of PSA in the blood but doesn't provide precise diagnostic information about the condition of the prostate.
The PSA test is only one tool used to screen for early signs of prostate cancer. Another common screening test, usually done in addition to a PSA test, is a digital rectal exam. In this test, your doctor inserts a lubricated, gloved finger into your rectum to reach the prostate.
By feeling or pressing on the prostate, the doctor may be able to judge whether it has abnormal lumps or hard areas. Neither the PSA test nor the digital rectal exam provides enough information for your doctor to diagnose prostate cancer.
Abnormal results in these tests may lead your doctor to recommend a prostate biopsy. During a prostate biopsy, samples of prostate tissue are removed for laboratory examination. A diagnosis of cancer is based on the biopsy results. For those who have already been diagnosed with prostate cancer, the PSA test may be used to:. Medical organizations vary in their recommendations about who should — and who shouldn't — get a PSA screening test. Discussing with your doctor the benefits, limitations and potential risks of the PSA test can help you make an informed decision.
A PSA test may help detect prostate cancer at an early stage. Cancer is easier to treat and is more likely to be cured if it's diagnosed in its early stages. But to judge the benefit of the test, it's important to know if early detection and early treatment will improve treatment outcomes and decrease the number of deaths from prostate cancer. A key issue is the typical course of prostate cancer. Prostate cancer usually progresses slowly over many years.
Therefore, it's possible to have prostate cancer that never causes symptoms or becomes a medical problem during your lifetime. The potential risks of the PSA test are essentially related to the choices you make based on the test results, such as the decision to undergo further testing and treatment for prostate cancer.
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