PSA Testing
Prostate Specific Antigen (PSA) is a protein produced only by prostate
tissue. PSA is released into the bloodstream and can be measured by a
routine blood test. While PSA production is normal for a healthy prostate,
elevated PSA levels in the blood could be an indicator of cancer, prostate
infection, or benign enlargement of the prostate.
The PSA Test
The PSA test measures levels of PSA in the blood. This test serves three primary functions:
-
Prostate Cancer Screening
The PSA test is used in combination with a digital rectal exam to screen for prostate cancer. An elevated PSA level (>2.5 ng/ml) is suggestive of prostate cancer. -
Prognosis
Once prostate cancer is diagnosed, PSA is used as a prognostic factor to help stage the cancer. The degree of elevation generally indicates the amount of cancer present. Men with early-stage prostate cancer tend to have a low PSA (<10 ng/ml), while those with advanced prostate cancers tend to have a higher PSA. The higher the PSA, the more likely it is that cancer has broken through the capsule of the prostate and spread to the lymph nodes and/or other parts of the body. -
Follow-up
Once prostate cancer is treated, PSA levels are measured to monitor the success of the treatment. Following treatment, the PSA should be very low and stable. A rising PSA is generally indicative of a recurrence.
Prostate Cancer Risk Stratification
After a prostate cancer diagnosis the doctor needs to be able to estimate the likelihood of cancer spreading outside the prostate. The three factors used to determine the estimate include:
- The PSA
- Cancer staging based on a rectal exam
- The Gleason Score, a 1-to-5 grading system used to determine the aggressiveness of a prostate cancer.