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Prostate Specific Antigen

Prostate specific antigen (PSA) is a screening test for prostate cancer.  The test measures a substance made by prostate cells.  Small amounts of PSA leak naturally into the blood.  When a man has prostate cancer, ducts in the prostate become blocked so more PSA leaks into the blood, thus raising the PSA level found on the blood test.

The PSA test is obtained by drawing blood from the arm.  A lab then measures the level of the substance.  The ordering doctor will have the lab results in about a week.

The PSA test is used by doctors, along with a digital rectal exam to screen men over 50 for prostate cancer.  (Screening tests are done on persons who are not having symptoms to help doctors detect cancer early).  The PSA is also used to monitor men who have prostate cancer to see if the cancer has come back.

Screening for prostate cancer with the PSA is controversial.  Although three types of screening tests are available, each test can produce false results, which could lead to unnecessary treatments, which can be harmful.  Research is being done to determine the best method of screening for prostate cancer.  Talk with your doctor about what is best for you.

Screening Guidelines

American Cancer Society (ACS)

The ACS recommends both the PSA and digital rectal exam (DRE) should be offered annually, beginning at age 50, and to younger men who are at high risk.  Information should be provided to patients regarding potential risks and benefits of intervention.

Men in high risk groups, such as those with a strong family history (two or more first degree relatives with prostate cancer) or African Americans, may begin screening at a younger age, (45 years of age).  More data on the precise age to start screening are needed for men at high risk.

National Cancer Institute (NCI)

The NCI states there is insufficient evidence to establish whether a decrease in mortality for prostate cancer occurs with screening by digital rectal examination, transrectal ultrasound, or serum markers, including the PSA.  Doctors are studying these tests to find out how useful they are.

The US Preventative Services Task Force

The US Preventative Service Task Force does not recommend routine screening with the digital rectal exam, PSA blood test, or transrectal ultrasound.

Patients who request screening should be given information about the potential benefits and harms of early detection and treatment and discuss these issues with their doctor.

If screening is performed, the best approach is to screen with digital rectal exam and the PSA blood test.