When prostate cancer is caught early, it has a better chance of being cured. For most men, this requires regular screening tests when symptoms are not present. The most common screening tests are digital rectal exam (DRE) and prostate-specific antigen (PSA) blood testing.
However, opinions about screening for prostate cancer vary. Talk to your doctor about whether you should be screened and which method is best for you. Sometimes both methods are recommended.
If your doctor suspects cancer, a biopsy or further PSA testing may be performed.
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The simplest and oldest screening test for prostate cancer is the digital rectal exam (DRE). The health care provider gently inserts a gloved forefinger into the rectum to feel the prostate gland for enlargement or other abnormalities, such as a lump.
The DRE is not a definitive cancer test, but regular exams help detect changes in the prostate over time that might signal cancer or pre-cancerous conditions. Although this test usually is not as reliable as the PSA blood test, a DRE may be able to find cancer if a man has a normal PSA level. A DRE also may be used to tell if prostate cancer has spread or returned after treatment.
DREs are recommended as part of a man's annual physical exam beginning at age 50.
Prostate-specific antigen (PSA) is a glycoprotein produced by the epithelial cells of the prostate gland. It is found mostly in semen, but a small amount is in the blood as well.
A blood test measures the amount of PSA circulating in the blood, expressed in nanograms per milliliter (ng/mL). This level is used to assess cancer risk. A higher PSA level usually means a higher chance of having prostate cancer.
However, the test is not foolproof. PSA is specific to prostate tissue but not cancer, so low levels do not always mean cancer is not present. Higher than normal levels can be caused by factors other than cancer, including:
- Enlarged prostate, also called benign prostatic hyperplasia (BPH). Swelling of the prostate is normal in many older men.
- Age: PSA levels normally go up slowly as men age.
- Infection or inflammation of the prostate, which also is called prostatitis.
- PSA may rise briefly after ejaculation, then return to normal levels.
On the other hand, certain conditions may make PSA levels low, even when a man has prostate cancer. These include:
- Some drugs used to treat BPH or other conditions
- Certain herbal medicines or supplements
Despite its limitations, PSA testing has helped detect cancer in countless men. In 1984, before PSA testing was available, the chance of finding early prostate cancer was about 50 percent. In 1993, after PSA testing became widely used, that figure jumped to more than 90 percent.
Men with very low PSA levels may need to be re-tested every two years. However, if PSA is higher, the doctor may recommend more frequent testing.
Because prostate cancer develops slowly, physicians usually do not recommend the PSA test for men who are older than 75 or have other significant health issues.
Read more about screening in the section on Prevention.
Additional PSA testing
Besides screening, PSA testing can be used in other ways in men who have been diagnosed with prostate cancer. For instance, it may:
- Help doctors plan your treatment or further testing
- Determine if cancer has metastasized (spread beyond the prostate)
- Find out if treatment is working or cancer has returned
- Aid in active surveillance (also called watchful waiting) by showing if cancer is growing
If your doctor suspects prostate cancer, a biopsy (removal of small pieces of prostate tissue to examine under a microscope) may be performed. This is the only way to definitively diagnose prostate cancer.
Biopsies for prostate cancer are done in a doctor's office or other facility as an outpatient procedure. You usually do not have to spend the night in the hospital.
Before the biopsy, you will have an enema to make your bowels move. Then you will be given an antibiotic to prevent infection. A local anesthetic like dentists use, often lidocaine, is injected into the area close to the prostate to make the procedure more comfortable.
A small transrectal ultrasound (TRUS) probe with a tiny camera is inserted into the rectum so the doctor can view the prostate on a video screen. This takes about 10 minutes. Using this image as a guide, the physician injects a thin needle through the wall of the rectum into the prostate.
Then, a fine-gauge, spring-loaded biopsy needle is used to remove 10 to 12 tiny samples of tissue from specific, predetermined areas on the prostate gland.
While side effects usually are mild, they may include:
- Blood in semen for up to two months
- Orange or rust-colored urine
- Light rectal bleeding
Less than 1 percent of men develop a blood infection that is resistant to the preventive antibiotics given before the procedure. These patients may need to be admitted to the hospital and receive stronger antibiotics.
Sometimes a biopsy will not find cancer, even if it is there. If your doctor is concerned you have prostate cancer based on follow-up testing, a second biopsy may be performed.
The biopsy specimens take about three to seven days to process.
Last reviewed on 5/27/10
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