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Prostate Cancer Diagnosis: What you should know. 

The American Urological Association advises the following regarding the use of the PSA test:

• Men should begin yearly PSA testing at age 50, or sooner if they have a strong family history of prostate cancer.  African American men, or men with a strong family history should begin screening at age 40.  
•    Your physician should consider doing a PSA test if; PSA is 4.0 ng/mL or higher, if the level significantly increases from one PSA test to the next, or if the digital rectal exam is negative.  -JAMA 3.22.00 p. 1557

• PSA makes it possible to diagnose up to 80 % of prostate cancers while the are still confined to the gland. Prior to PSA testing only approximately 30% were diagnosed early. 
• PSA is a protein found in the prostate gland.  It is manufactured by the gland to liquefy the seminal fluids. 
• PSA that a blood test measures is produced by both normal and diseased prostate tissue.  
• Other reasons PSA can be elevated are the following: urinary retention, prostatitis (infection/inflammation ), prostate massage, and ejaculation. PSA testing should be delayed for as long as 6 weeks following one of these to allow for more accurate measure.  

• The drug Finasteride (Propecia or Proscar) artificially lowers PSA. 
• The positive predictive value of the combination of PSA and Digital rectal exam in identifying prostate cancer  is approximately 60%. 
• When a suspicious DRE and PSA test are obtained,  the diagnostic procedure of choice is a transrectal ultrasound.  This takes place with the placement a ultrasound probe across the rectum.  
• Prostate biopsies are taken in a pattern referred to as a sextant.  This method utilizes a grid to obtain one specimen from each area of the prostate, the apex, middle, and posterior base.  The biopsy occurs with an 18 gauge needle very similar to the size of a needle utilized to draw your blood, just longer.  The needle is guided into each grid sector by utilizing the ultrasound to guide it into the proper area

• single set of biopsies has at least a 25 % chance of being a false negative.  What does this mean?  This means that for a biopsy set, with at least one biopsy sample from each of the three areas, these samples may have no visible sign of cancer on microscopic evaluation, leading to a report of negative.  However, 25 % of the time these samples may have missed the cancerous tissue.  For this reason, researchers are recommending that additional biopsies be taken. However, patients should know that the additional biopsies can  lead to additional discomfort and risk. 
• PSA levels of 4.0 ng/mL are considered the upper limit of normal.  However, 20% of those with prostate cancer have a number below 4.0 ng/mL
• Researchers are trying to develop additional criteria to accurately predict prostate cancer. Much debate surrounds issues such as adjusting the PSA normal limits for age and race.  No consensus has been reached on these issues.
• PSA Velocity: This is a measure of the rate of rise of PSA over a period of time. This partially eliminates the variability that can occur in multiple PSA readings that can occur from day to day.  Some studies have shown a 15-20% day to day variation. Experts don't yet agree on the value of this calculation, and it appears to lose value for PSA values over 4.0 ng/mL.  

• PSA Density: This is a calculation that utilizes PSA level divided by prostate volume.  The prostate volume is estimated by utilizing ultrasound.  It is important the remember that ultrasound results are dependant on the quality of the  technique that the ultrasound technician has.  The value of this test is of much debate, because of daily variations is PSA level (up to 20%) and prostate volume (10%-30%).
• Free PSA (percent free PSA):  Substances that circulate in the blood stream sometimes are connected to other substances.  This is referred to as binding.  This binding is determined by complex chemical properties that all substances have. Some substances are more "sticky" and are found bound to other substances in the blood or body tissues.  Binding is the means in which many vitamins and drugs circulate around the body. It is like having an escort. PSA normally circulates with an escort in the bound fashion.  There is a small portion of PSA that circulated free, or unbound.  For some unexplained reason, researchers have shown that when  this free PSA is measured, it appears to be lower in mean with prostate cancer.  This measurement when compared  with the total PSA level, can increase the value of the measurements, and eliminate up to 20% of "unnecessary" biopsies.  However, the current free PSA studies were utilized with the single sextant set of biopsies. Remember, that the single sextant set had a 25 % false negative result.  Therefore, it is believed that free PSA is a tool for physicians to use in deciding whether to perform 2nd biopsies in men with normal digital rectal exam and PSA between 4 ng/mL and 10ng/mL. 
  

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