A PSA (prostate-specific antigen) test is a blood test commonly used to screen men for prostate cancer. PSA is a protein is made by the prostate gland. The test measures how much PSA is in a man’s blood.

The prostate gland is found in men only and is about the size of a walnut. It produces and stores the fluid that carries sperm. The prostate is positioned just below the bladder, near the rectum (the last part of the bowel before the anus), and surrounds the urethra, which is the tube that drains urine from the bladder.

When there is a higher-than-normal level of PSA in a man’s blood or his PSA level has increased over time, it is an indication that he may have prostate cancer or a noncancerous enlargement of the prostate. If a PSA test is abnormal, a doctor may order other tests, including a prostate gland biopsy to check for cancerous cells. This is because the PSA test is not specific for cancer.

PSA testing can help find cancer at an early stage, when it is relatively small and before it causes symptoms. The PSA test is also used to monitor existing prostate cancer to determine whether it has spread. A serial PSA blood test is usually given every 3 months to 1 year as part of the Gleason score, a cancer grading system, to evaluate the severity of prostate cancer.

Another kind of common prostate cancer screening is a digital rectal exam. This is performed by a doctor or nurse, who uses a finger to feel the prostate gland through the rectum in order to check the gland’s shape and to search for hard spots.

ADDITIONAL FACTS

  1. Nine out of 10 men diagnosed with prostate cancer have localized cancer that has not spread outside the prostate gland. Most men with localized prostate cancer survive the disease, no matter what the treatment.
  2. There are four common treatments for prostate cancer. These are (1) watchful waiting, which means carefully monitoring the cancer with regular checkups; (2) surgical removal of the prostate called radical prostatectomy; (3) radiation, administered in the form of either external beam or brachytherapy (seeding); and (4) hormone treatment.
  3.  Doctors are debating whether PSA screening is necessary for men over age 70, because most prostate cancers grow very slowly and spread only after many years.