Prostate-Specific Antigen (PSA) Test - National Cancer Institute
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`Prostate-Specifc Antigen (PSA) Test
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`ON THIS PAGE
`What is the PSA test?
`
`Is the PSA test recommended for prostate cancer screening?
`
`What is a normal PSA test result?
`
`What if a screening test shows an elevated PSA level?
`
`What are some of the limitations and potential harms of the PSA test for prostate cancer screening?
`
`What research has been done to study prostate cancer screening?
`
`How is the PSA test used in men who have been treated for prostate cancer?
`
`What does an increase in PSA level mean for a man who has been treated for prostate cancer?
`
`How are researchers trying to improve the PSA test?
`
`• • • • • • • • •
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`What is the PSA test?
`
`Prostate-specifc antigen, or PSA, is a protein produced by cells of the prostate gland. The PSA test
`measures the level of PSA in a man’s blood. For this test, a blood sample is sent to a laboratory for
`analysis. The results are usually reported as nanograms of PSA per milliliter (ng/mL) of blood.
`
`The blood level of PSA is often elevated in men with prostate cancer, and the PSA test was originally
`approved by the FDA in 1986 to monitor the progression of prostate cancer in men who had already been
`diagnosed with the disease. In 1994, the FDA approved the use of the PSA test in conjunction with a digital
`rectal exam (DRE) to test asymptomatic men for prostate cancer. Men who report prostate symptoms often
`undergo PSA testing (along with a DRE) to help doctors determine the nature of the problem.
`
`https://www.cancer.gov/types/prostate/psa-fact-sheet[4/11/2017 9:41:45 AM]
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`Prostate-Specific Antigen (PSA) Test - National Cancer Institute
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`In addition to prostate cancer, a number of benign (not cancerous) conditions can cause a man’s PSA level
`to rise. The most frequent benign prostate conditions that cause an elevation in PSA level are prostatitis
`(infammation of the prostate) and benign prostatic hyperplasia (BPH) (enlargement of the prostate). There
`is no evidence that prostatitis or BPH leads to prostate cancer, but it is possible for a man to have one or
`both of these conditions and to develop prostate cancer as well.
`
`Is the PSA test recommended for prostate cancer screening?
`
`Until recently, many doctors and professional organizations encouraged yearly PSA screening for men
`beginning at age 50. Some organizations recommended that men who are at higher risk of prostate cancer,
`including African American men and men whose father or brother had prostate cancer, begin screening at
`age 40 or 45. However, as more has been learned about both the benefts and harms of prostate cancer
`screening, a number of organizations have begun to caution against routine population screening. Although
`some organizations continue to recommend PSA screening, there is widespread agreement that any man
`who is considering getting tested should frst be informed in detail about the potential harms and benefts.
`
`Currently, Medicare provides coverage for an annual PSA test for all Medicare-eligible men age 50 and
`older. Many private insurers cover PSA screening as well.
`
`What is a normal PSA test result?
`
`There is no specifc normal or abnormal level of PSA in the blood. In the past, most doctors considered
`PSA levels of 4.0 ng/mL and lower as normal. Therefore, if a man had a PSA level above 4.0 ng/mL,
`doctors would often recommend a prostate biopsy to determine whether prostate cancer was present.
`
`However, more recent studies have shown that some men with PSA levels below 4.0 ng/mL have prostate
`cancer and that many men with higher levels do not have prostate cancer (1). In addition, various factors
`can cause a man’s PSA level to fuctuate. For example, a man’s PSA level often rises if he has prostatitis
`or a urinary tract infection. Prostate biopsies and prostate surgery also increase PSA level. Conversely,
`some drugs—including fnasteride and dutasteride, which are used to treat BPH—lower a man’s PSA level.
`PSA level may also vary somewhat across testing laboratories.
`
`Another complicating factor is that studies to establish the normal range of PSA levels have been
`conducted primarily in populations of white men. Although expert opinions vary, there is no clear
`consensus regarding the optimal PSA threshold for recommending a prostate biopsy for men of any racial
`or ethnic group.
`
`In general, however, the higher a man’s PSA level, the more likely it is that he has prostate cancer.
`Moreover, continuous rise in a man’s PSA level over time may also be a sign of prostate cancer.
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`Prostate-Specific Antigen (PSA) Test - National Cancer Institute
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`What if a screening test shows an elevated PSA level?
`
`If a man who has no symptoms of prostate cancer chooses to undergo prostate cancer screening and is
`found to have an elevated PSA level, the doctor may recommend another PSA test to confrm the original
`fnding. If the PSA level is still high, the doctor may recommend that the man continue with PSA tests and
`DREs at regular intervals to watch for any changes over time.
`
`If a man’s PSA level continues to rise or if a suspicious lump is detected during a DRE, the doctor may
`recommend additional tests to determine the nature of the problem. A urine test may be recommended to
`check for a urinary tract infection. The doctor may also recommend imaging tests, such as a transrectal
`ultrasound, x-rays, or cystoscopy.
`
`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);
`however, the needles may also be inserted through the skin between the scrotum and the anus
`(transperineal 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.
`
`What are some of the limitations and potential harms of the PSA test
`for prostate cancer screening?
`
`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. Finding a small
`tumor, however, may not necessarily reduce a man’s chance of dying from prostate cancer. Some tumors
`found through PSA testing grow so slowly that they are unlikely to threaten a man’s life. Detecting tumors
`that are not life threatening is called “overdiagnosis,” and treating these tumors is called “overtreatment.”
`
`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 fow), problems with bowel function,
`erectile dysfunction (loss of erections, or having erections that are inadequate for sexual intercourse), and
`infection.
`
`In addition, fnding 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 occurs when
`a man’s PSA level is elevated but no cancer is actually present. 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
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`Prostate-Specific Antigen (PSA) Test - National Cancer Institute
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`can be harmful. Possible side effects of biopsies include serious infections, pain, and bleeding.
`
`Most men with an elevated PSA level turn out not to have prostate cancer; only about 25 percent of men
`who have a prostate biopsy due to an elevated PSA level actually have prostate cancer (2).
`
`A false-negative test result occurs when a man’s PSA level is low even though he actually has prostate
`cancer. 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.
`
`What research has been done to study prostate cancer screening?
`
`Several randomized trials of prostate cancer screening have been carried out. One of the largest is the
`Prostate, Lung, Colorectal, and Ovarian (PLCO) Cancer Screening Trial, which NCI conducted to
`determine whether certain screening tests can help reduce the numbers of deaths from several common
`cancers. In the prostate portion of the trial, the PSA test and DRE were evaluated for their ability to
`decrease a man’s chances of dying from prostate cancer.
`
`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.
`
`A second large trial, the European Randomized Study of Screening for Prostate Cancer (ERSPC),
`compared prostate cancer deaths in men randomly assigned to PSA-based screening or no screening. As
`in the PLCO, men in ERSPC who were screened for prostate cancer had a higher incidence of the disease
`than control men. In contrast to the PLCO, however, men who were screened had a lower rate of death
`from prostate cancer (4).
`
`The United States Preventive Services Task Force has analyzed the data
`from the PLCO, ERSPC, and other trials and estimated that, for every
`1,000 men ages 55 to 69 years who are screened every 1 to 4 years for a
`decade (5):
`
`VIEW
`INFOGRAPHIC
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`0 to 1 death from prostate cancer would be avoided.
`
`100 to 120 men would have a false-positive test result that leads to a
`biopsy, and about one-third of the men who get a biopsy would
`experience at least moderately bothersome symptoms from the
`biopsy.
`
`110 men would be diagnosed with prostate cancer. About 50 of these
`men would have a complication from treatment, including erectile dysfunction in 29 men, urinary
`
`• •
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`•
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`Prostate-Specific Antigen (PSA) Test - National Cancer Institute
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`incontinence in 18 men, serious cardiovascular events in 2 men, deep vein thrombosis or pulmonary
`embolism in 1 man, and death due to the treatment in less than 1 man.
`
`How is the PSA test used in men who have been treated for prostate
`cancer?
`
`The PSA test is used to monitor patients who have a history of prostate cancer to see if their cancer has
`recurred (come back). If a man’s PSA level begins to rise after prostate cancer treatment, it may be the frst
`sign of a recurrence. Such a “biochemical relapse” typically appears months or years before other clinical
`signs and symptoms of prostate cancer recurrence.
`
`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. The doctor may look for a trend of rising PSA
`level over time rather than a single elevated PSA level.
`
`What does an increase in PSA level mean for a man who has been
`treated for prostate cancer?
`If a man’s PSA level rises after prostate cancer treatment, his doctor will consider a number of factors
`before recommending further treatment. Additional treatment based on a single PSA test is not
`recommended. Instead, a rising trend in PSA level over time in combination with other findings, such as an
`abnormal result on imaging tests, may lead a man’s doctor to recommend further treatment.
`
`How are researchers trying to improve the PSA test?
`
`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.
`Some of the methods being studied include:
`
`•
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`•
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`•
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`Free versus total PSA. The amount of PSA in the blood that is “free” (not bound to other proteins)
`divided by the total amount of PSA (free plus bound). Some evidence suggests that a lower proportion
`of free PSA may be associated with more aggressive cancer.
`PSA density of the transition zone. The blood level of PSA divided by the volume of the transition
`zone of the prostate. The transition zone is the interior part of the prostate that surrounds the urethra.
`Some evidence suggests that this measure may be more accurate at detecting prostate cancer than
`the standard PSA test.
`Age-specific PSA reference ranges. Because a man’s PSA level tends to increase with age, it has
`been suggested that the use of age-specific PSA reference ranges may increase the accuracy of PSA
`tests. However, age-specific reference ranges have not been generally favored because their use may
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`Prostate-Specific Antigen (PSA) Test - National Cancer Institute
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`delay the detection of prostate cancer in many men.
`PSA velocity and PSA doubling time. PSA velocity is the rate of change in a man’s PSA level over
`time, expressed as ng/mL per year. PSA doubling time is the period of time over which a man’s PSA
`level doubles. Some evidence suggests that the rate of increase in a man’s PSA level may be helpful in
`predicting whether he has prostate cancer.
`Pro-PSA. Pro-PSA refers to several different inactive precursors of PSA. There is some evidence that
`pro-PSA is more strongly associated with prostate cancer than with BPH. One recently approved test
`combines measurement of a form of pro-PSA called [-2]proPSA with measurements of PSA and free
`PSA. The resulting “prostate health index” can be used to help a man with a PSA level of between 4
`and 10 ng/mL decide whether he should have a biopsy.
`
`Selected References
`1. Thompson IM, Pauler DK, Goodman PJ, et al. Prevalence of prostate cancer among men with a
`prostate-specifc antigen level < or =4.0 ng per milliliter. New England Journal of Medicine
`2004;350(22):2239-2246. [PubMed Abstract]
`
`2. Barry MJ. Clinical practice. Prostate-specifc-antigen testing for early diagnosis of prostate cancer.
`New England Journal of Medicine 2001;344(18):1373-1377. [PubMed Abstract]
`
`3. Andriole GL, Crawford ED, Grubb RL, et al. Prostate cancer screening in the randomized Prostate,
`Lung, Colorectal, and Ovarian Cancer Screening Trial: mortality results after 13 years of follow-up.
`Journal of the National Cancer Institute 2012;104(2):125-132. [PubMed Abstract]
`
`4. Schröder FH, Hugosson J, Roobol MJ, et al. Prostate-cancer mortality at 11 years of follow-up. New
`England Journal of Medicine 2012;366(11):981-990. [PubMed Abstract]
`
`5. Moyer VA on behalf of the U.S. Preventive Services Task Force. Screening for prostate cancer: U.S.
`Preventive Services Task Force recommendation statement. Annals of Internal Medicine 2012;
`157(2):120–134. [PubMed Abstract]
`
`Related Resources
`Understanding Laboratory Tests
`Prostate Cancer—Patient Version
`Prostate, Lung, Colorectal and Ovarian Cancer Screening Trial
`Tumor Markers
`Understanding Prostate Changes: A Health Guide for Men
`What You Need To Know About™ Prostate Cancer
`Prostate Cancer Screening (PDQ®)
`
`Reviewed: July 24, 2012
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`Prostate-Specific Antigen (PSA) Test - National Cancer Institute
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