Source: National Cancer Institute Research, www.cancer.gov
Screening is looking for cancer before a person has any symptoms. This can help find cancer at an early stage. When abnormaltissue or cancer is found early, it may be easier to treat. By the time symptoms appear, cancer may have begun to spread.
Scientists are trying to better understand which people are more likely to get certain types of cancer. They also study the things we do and the things around us to see if they cause cancer. This information helps doctors recommend who should be screened for cancer, which screening tests should be used, and how often the tests should be done.
It is important to remember that your doctor does not necessarily think you have cancer if he or she suggests a screening test. Screening tests are given when you have no cancer symptoms. Screening tests may be repeated on a regular basis.
If a screening test result is abnormal, you may need to have more tests done to find out if you have cancer. These are called diagnostic tests.
The prostate is a
gland in the male
reproductive system located just
below the bladder (the organ that
collects and empties urine) and in
front of the rectum (the lower part
of the intestine). It is about the
size of a walnut and surrounds part of the urethra (the tube that empties urine from the
bladder). The prostate gland produces fluid that makes up part of semen.
As men age, the prostate may get bigger. A bigger prostate may block the
flow of urine from the bladder and cause problems with sexual function. This condition is called benign prostatic hyperplasia (BPH), and although
it is not cancer, surgery may be
needed to correct it. The symptoms
of benign prostatic hyperplasia or of other problems in the prostate may be
similar to symptoms of prostate cancer.
See the following PDQ summaries for more information about prostate cancer:
Prostate cancer is found mainly in older men. Although the number of men with prostate cancer is large, most men diagnosed with this disease do not die from it. Prostate cancer occurs more often in African-American men than in white men. African-American men with prostate cancer are more likely to die from the disease than white men with prostate cancer.
Anything that increases a person's chance of developing a disease is called a risk factor. Risk factors for prostate cancer include the following:
Some screening tests are used because they have been shown to be helpful both in finding cancers early and decreasing the chance of dying from these cancers. Other tests are used because they have been shown to find cancer in some people; however, it has not been proven in clinical trials that use of these tests will decrease the risk of dying from cancer.
Scientists study screening tests to find those with the fewest risks and most benefits. Cancer screening trials also are meant to show whether early detection (finding cancer before it causes symptoms) decreases a person's chance of dying from the disease. For some types of cancer, finding and treating the disease at an early stage may result in a better chance of recovery.
Screening tests for prostate cancer are under study, and there are screening clinical trials taking place in many parts of the country. Information about ongoing clinical trials is available from the NCI Web site.
Digital rectal exam (DRE) is an exam of the rectum. The doctor or nurse inserts a lubricated, gloved finger into the lower part of the rectum to feel the prostate for lumps or anything else that seems unusual.
A prostate-specific antigen (PSA) test is a test that measures the level of PSA in the blood. PSA is a substance made mostly by the prostate that may be found in an increased amount in the blood of men who have prostate cancer. The level of PSA may also be high in men who have an infection or inflammation of the prostate or benign prostatic hyperplasia (BPH; an enlarged, but noncancerous, prostate).
If a man has a high PSA level and a biopsy of the prostate does not show cancer, a prostate cancer gene 3 (PCA3) test may be done. This test measures the amount of PCA3 in the urine. If the PCA3 level is high, another biopsy may help diagnose prostate cancer.
Scientists are studying the combination of PSA testing and digital rectal exam as a way to get more accurate results from the screening tests.
Decisions about screening tests can be difficult. Not all screening tests are helpful and most have risks. Before having any screening test, you may want to discuss the test with your doctor. It is important to know the risks of the test and whether it has been proven to reduce the risk of dying from cancer.
Screening may not improve your health or help you live longer if you have cancer that has already spread to the area outside of the prostate or to other places in your body.
Some cancers never cause symptoms or become life-threatening, but if found by a screening test, the cancer may be treated. Finding these cancers is called overdiagnosis. It is not known if treatment of these cancers would help you live longer than if no treatment were given, and treatments for cancer, such as surgery and radiation therapy, may have serious side effects.
Some studies of patients with prostate cancer showed these patients had a higher risk of death from cardiovascular (heart and blood vessel) disease or suicide. The risk was greatest the first year after diagnosis.
If a PSA test is higher than normal, a biopsy of the prostate may be done. Complications from a biopsy of the prostate may include fever, pain, blood in the urine or semen, and urinary tractinfection. Even if a biopsy shows that a patient does not have prostate cancer, he may worry more about developing prostate cancer in the future.
Screening test results may appear to be normal even though prostate cancer is present. A man who receives a false-negative test result (one that shows there is no cancer when there really is) may delay seeking medical care even if he has symptoms.
Screening test results may appear to be abnormal even though no cancer is present. A false-positive test result (one that shows there is cancer when there really isn't) can cause anxiety and is usually followed by more tests, (such as biopsy) which also have risks.
Your doctor can advise you about your risk for prostate cancer and your need for screening tests.