How is Prostate Cancer Detected?
Prostate Cancer Symptoms
In its early states, prostate cancer often doesn't produce any symptoms. Symptoms that may indicate prostate cancer — and should be followed up with a visit to the doctor — include:
- Frequent urination, especially at night
- Urgency in urinating
- Trouble starting your urine stream
- A weak or interrupted urine stream
- Pain or burning during urination
- A feeling that your bladder doesn't empty completely
- Blood in the urine
- A nagging pain in the back, hips or pelvis
Although these symptoms can be caused by prostate cancer, they also can be caused by other conditions that are not cancer. A very common one is benign prostatic hyperplasia (BPH). As men age, the prostate often enlarges and can press on and block the urethra and bladder, producing some of the symptoms described above. BPH can be successfully treated with medication or surgery.
Prostate Cancer Screening
The two most commonly used methods for detecting prostate cancer are the digital rectal examination (DRE) and the prostate-specific antigen (PSA) test. As a single screening method, the PSA test is more effective than the DRE, but using both increases the chance of detecting cancer when present.
Digital Rectal Examination
During a digital rectal examination, a doctor inserts a gloved, lubricated finger into a man's rectum to feel for any irregular or abnormally firm area in the prostate. Many, but not all, prostate cancers can be detected this way. The DRE also can be used to monitor the progress of treatment.
Prostate-Specific Antigen Test
Prostate-specific antigen (PSA) is a protein in the blood that is produced only by prostate cells. PSA reflects the volume of both benign and malignant prostate tissue. The higher the PSA level, the more likely it is that prostate cancer is present.
PSA test results are reported as nanograms per milliliter (ng/ml). Results less than 4.0 ng/ml usually are considered normal; values over this are regarded as high. The average PSA level increases with age, so some values — even below 4.0 ng/ml for men younger than 60 — should be cause to seek a more thorough evaluation. Ask your doctor for acceptable values for your age.
Having a high PSA doesn't always mean that you have cancer. Certain activities and conditions can produce a high PSA, including benign prostatic hyperplasia; ejaculation up to three days prior to the testing; a recent prostate biopsy; an acute urinary tract infection; and prostatitis, an inflammation of the prostate that usually is treated successfully with antibiotics.
Certain medications and herbal preparations may lower PSA levels, possibly masking the presence of early prostate cancer. These medications include finasteride (Proscar or Propecia); saw palmetto, an herb some men use to treat benign prostatic hyperplasia; and PC-SPES, an herbal mixture that contains saw palmetto. Tell your doctor if you are taking any of these.
PSA levels may also be affected by activities such bicycle riding or other vigorous exercise.
There are two modifications of the PSA test that can increase its effectiveness:
- Percent free-PSA Also called PSA II, this test indicates how much PSA circulates unbound in the blood (free-PSA), and how much is bound together with other blood proteins. Men with prostate cancer are more likely to have low levels of free-PSA. A free-PSA score below 10 percent may indicate prostate cancer. A score above 25 percent is more consistent with benign prostatic enlargement. Levels between 10 percent and 25 percent are indeterminate, but suggest the need for more monitoring or evaluation.
The percent free-PSA measure appears most useful when the total PSA level is between 4 and 10. The range of the percent free-PSA can vary with the assay or testing procedure used by the laboratory. This test is primarily used for the detection of prostate cancer.
- PSA velocity PSA velocity measures how quickly the PSA level rises over a period of time. Prostate cancer is more likely if the PSA rises more than 0.75 ng/ml per year. To be accurate, there should be a minimum of three tests over a period of 18 months or less to determine the velocity.
While the PSA test is used mostly for early detection, it has value in other situations. Men with higher PSA scores are more likely to have cancer that has spread beyond the prostate. In such cases, localized treatments such as radical prostatectomy — an operation to remove the prostate — or radiation therapy are less likely to be successful. The PSA test also is used to monitor treatment effectiveness. Rising PSA levels after surgery or radiation, or during hormonal treatment, can provide an early sign that the cancer is recurring or continuing to grow.
The earlier and more rapid the rise of the PSA following localized treatment, the more likely the recurrence is due to cancer cells that are outside the prostate. However, some advanced cancers produce very little PSA, and other markers have to be used to monitor the status of the cancer.
Return to the Patient's Guide to Prostate Cancer Index:
UCSF Health medical specialists have reviewed this information. It is for educational purposes only and is not intended to replace the advice of your doctor or other health care provider. We encourage you to discuss any questions or concerns you may have with your provider.