Details of cancer screenings
Details of Prostate Cancer Screenings
refers to tests and exams used to find a disease, such as cancer, in people who do not have any symptoms. The goal of screening exams is to find cancers before they start to cause symptoms. For some types of cancer, screening can help find cancers in an early stage when they are more easily cured.
Prostate cancer can often be found early by testing the amount of prostate-specific antigen (PSA) in a man's blood. Another way to find prostate cancer is the digital rectal exam (DRE), in which the doctor puts a gloved finger into the rectum to feel the prostate gland. These 2 tests are described later on in more detail.
If the results of either one of these tests are abnormal, further testing is needed to see if there is a cancer. If prostate cancer is found as a result of screening with the PSA test or DRE, it will probably be at an earlier, more treatable stage than if no screening were done.
Since the use of early detection tests for prostate cancer became fairly common in the United States (about 1990), the prostate cancer death rate has dropped. But it isn't yet clear if this drop is a direct result of screening or if it might be caused by something else, like improvements in treatment.
There is no question that screening can help find many prostate cancers early, but there are limits to the prostate cancer screening tests used today. Neither the PSA test nor the DRE is 100% accurate. These tests can sometimes have abnormal results even when a man does not have cancer (known as false positive
results). Normal results can also occur even when a man does have cancer (known as false negative
results). Unclear test results can cause confusion and anxiety. False-positive results can lead some men to have a prostate biopsy (with small risks of pain, infection, and bleeding) when they do not have cancer. And false-negative results can give some men a false sense of security even though they actually have cancer.
Another important issue is that even if screening detects a cancer, doctors often can't tell if the cancer is truly dangerous. Finding and treating all prostate cancers early might seem as if it would always be a good thing. But some prostate cancers grow so slowly that they would probably never cause problems. Because of an elevated PSA level, some men may be diagnosed with a prostate cancer that they would have never even known about at all. It would never have lead to their death, or even caused any symptoms.
But these men may still be treated with either surgery or radiation, either because the doctor can't be sure how quickly the cancer might grow and spread, or because the men are uncomfortable knowing they have cancer and not getting any treatment. Treatments like surgery and radiation can have urinary, bowel, and/or sexual side effects that may seriously affect a man's quality of life.
Men and their doctors may end up struggling over whether they need treatment or whether they might be able to be followed without being treated right away (an approach called watchful waiting
or active surveillance
). Even when men are not treated right away, they still need regular blood tests and prostate biopsies to determine the need for future treatment. These tests are linked with risks of anxiety, pain, infection, and bleeding.
To help figure out if prostate cancer screening is worthwhile, doctors are conducting large studies to see if early detection tests will lower the risk of death from prostate cancer. The most recent results from 2 large studies were conflicting, and didn't offer clear answers.
Early results from a study done in the United States found that annual screening with PSA and DRE detected more prostate cancers than in men not screened, but it did not lower the death rate from prostate cancer. A European study did find a lower risk of death from prostate cancer with PSA screening (done about once every 4 years), but the researchers estimated that about 1,050 men would need to invited to be screened (and 37 treated) to prevent one death from prostate cancer. Neither of these studies has shown that PSA screening helps men live longer (lowered the overall death rate).
Prostate cancer is often a slow-growing cancer, so the effects of screening in these studies may become clearer in the coming years. Both of these studies are being continued to see if longer follow-up will give clearer results. Several other large studies of prostate cancer screening are now going on as well.
At this time, the American Cancer Society (ACS) recommends that men thinking about prostate cancer screening should make informed decisions based on available information, discussion with their doctor, and their own views on the benefits and side effects of screening and treatment (see below).
Until more information is available, you and your doctor can decide whether you should have tests to screen for prostate cancer. There are many factors to take into account, including your age and health. If you are young and develop prostate cancer, it may shorten your life if it is not caught early. Screening men who are older or in poor health in order to find early prostate cancer is less likely to help them live longer. This is because most prostate cancers are slow-growing, and men who are older or sicker are likely to die from other causes before their prostate cancer grows enough to cause problems.
For additional information on prostate cancer screenings, please visit
Clinical Tests That Can Find Prostate Cancer
1) Prostate-Specific Antigen (PSA) Blood Test
Prostate-specific antigen (PSA) is a substance made by cells in the prostate gland (it is made by normal cells and cancer cells). Although PSA is mostly found in semen, a small amount is also found in the blood. Most healthy men have levels under 4 ng/mL of blood. The chance of having prostate cancer goes up as the PSA level goes up.
When prostate cancer develops, the PSA level usually goes above 4. Still, a level below 4 does not mean that cancer is not present -- about 15% of men with a PSA below 4 will have prostate cancer on biopsy. Men with a PSA level in the borderline range
between 4 and 10, have about a 1 in 4 chance of having prostate cancer. If the PSA is more than 10, the chance of having prostate cancer is over 50%.
If your PSA level is high, your doctor may advise either waiting a while and repeating the test, or getting a prostate biopsy to find out if you have cancer. Not all doctors use the same PSA cutoff point when advising whether to do a biopsy. Some may advise it if the PSA is 4 or higher, while others might recommend it at 2.5 or higher. Other factors, such as your age, race, and family history, may also come into play.
The PSA level can also be increased by things other than prostate cancer, such as:
An enlarged prostate
, such as with benign prostatic hyperplasia (BPH), a non-cancerous enlargement of the
prostate that many men get as they grow older
PSA levels will also normally go up slowly as you get older, even if you have no prostate
This term refers to infection or inflammation of the prostate gland, which may raise PSA levels.
can cause the PSA to go up for a short time, and then go down again. This is why some
healthcare professionals will suggest that men abstain from ejaculation for 2 days before testing.
Riding a bicycle:
Some studies have suggested that cycling may raise PSA levels (possibly because the seat
puts pressure on the prostate), although not all studies have found this.
Certain urologic procedures:
Some procedures done in a doctor's office that affect the prostate, such as a
prostate biopsy or cystoscopy, may result in higher PSA levels for a short time. Some studies have suggested that a digital rectal exam (DRE) might raise PSA levels slightly, although other studies have not found this. Still, if both a PSA test and a DRE are being done during a doctor visit, some doctors advise having the blood drawn for the PSA before having the DRE, just in case.
Taking testosterone (or other medicines that raise testosterone levels) may cause a rise
Some things cause PSA levels to go down (even when cancer is present), including:
used to treat BPH or urinary symptoms, such as finasteride (Proscar or Propecia) or
dutasteride (Avodart). You should tell your healthcare professional if you are taking these medicines, because they will lower PSA levels and require the healthcare professional to adjust the reading.
that are sold as dietary supplements may also mask a high PSA level. This is why it is
important to let your healthcare professional know if you are taking any type of supplement, even ones that are not necessarily meant for prostate health. Saw palmetto (an herb used by some men to treat BPH) does not seem to interfere with the measurement of PSA.
may also change PSA levels
Obese men tend to have lower PSA levels
Some recent research has suggested that men who take aspirin regularly may have lower PSA
levels. This effect may be greater in non-smokers. More research is needed to confirm this finding. If you take aspirin regularly (such as to help prevent heart disease), talk to your doctor before you stop taking it for any reason.
For men not known to have prostate cancer, it is not always clear if lowering the PSA is helpful. In some cases the factor that lowers the PSA may also lower a man's risk of prostate cancer. But in other cases, it might lower the PSA level without affecting a man's risk of cancer. This could actually be harmful, if it were to lower the PSA from an abnormal level to a normal one, as it might result in not detecting a cancer. This is why it is important to talk to your doctor about anything that might affect your PSA level.
2) Percent-free Prostate-Specific Antigen
PSA occurs in 2 major forms in the blood. One form is attached to blood proteins while the other circulates free
(unattached). The percent-free PSA (fPSA) is the ratio of how much PSA circulates free compared to the total
PSA level. The percentage of free PSA is lower in men who have prostate cancer than in men who do not.
This test is sometimes used to help decide if you should have a prostate biopsy if your PSA results are in the
borderline range (between 4 and 10). A lower percent-free PSA means that your likelihood of having prostate
cancer is higher and you should probably have a biopsy. Many health care professionals recommend biopsies for
men whose percent-free PSA is 10% or less, and advise that men consider a biopsy if it is between 10% and
25%. Using these cutoffs detects most cancers while helping some men to avoid unnecessary prostate biopsies.
This test is widely used, but not all health care professionals agree that 25% is the best cutoff point to decide on
A newer test, known as complexed PSA, measures the amount of PSA that is attached to other proteins. This test
is described in more detail at Prostate-Specific Antigen Velocity
The PSA velocity is not a separate test. It is a measure of how fast the PSA rises over time. Normally, PSA
levels go up slowly with age. Experts noticed that these levels can go up faster when cancer is present. When
this issue was looked at further, though, studies showed that the PSA velocity was not more helpful than the
PSA itself in finding prostate cancer. For this reason, the most recent ACS guideline on early detection of
prostate cancer does not recommend using the PSA velocity. Prostate-Specific Antigen Density
PSA levels are higher in men with larger prostate glands. The PSA density (PSAD) is sometimes used for men
with large prostate glands to try to adjust for this. The health care professional measures the volume (size) of the
prostate gland with transrectal ultrasound (discussed below) and divides the PSA number by the prostate
volume. A higher PSA density (PSAD) indicates greater likelihood of cancer. PSA density has not been shown
to be that useful. The percent-free PSA test has so far been shown to be more accurate.
Age-Specific Prostate-Specific Antigen Ranges
PSA levels are normally higher in older men than in younger men, even when there is no cancer. A PSA result
within the borderline range might be very worrisome in a 50-year-old man but cause less concern in an 80-year-
old man. For this reason, some health care professionals have suggested comparing PSA results with results
from other men of the same age.
But because the usefulness of age-specific PSA ranges is not well proven, most health care professionals and professional organizations (as well as the makers of the PSA tests) do not recommend their use at this time.
3) Digital Rectal Exam (DRE)
For a digital rectal exam (DRE), a health care professional inserts a gloved, lubricated finger into the rectum to feel for any bumps or hard areas on the prostate that might be cancer. The prostate gland is found just in front of the rectum, and most cancers begin in the back part of the gland, which can be felt during a rectal exam. This exam is uncomfortable, but it isn't painful and only takes a short time.
DRE is less effective than the PSA blood test in finding prostate cancer, but it can sometimes find cancers in men with normal PSA levels. For this reason, it may be included as a part of prostate cancer screening.
The DRE can also be used once a man is known to have prostate cancer to try to determine if it may have spread to nearby tissues and to detect cancer that has come back after treatment.
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