A man who decides with his physician to begin an early-detection program should understand both the types of tests available and their appropriate use.

Prostate Specific Antigen
PSA testing has had the greatest impact on the early detection of prostate cancer. PSA is a protein made only by prostate epithelial cells. Only small amounts leak from the normal prostate into the bloodstream where its presence can be detected through a blood sample in all men.  For reasons that are not completely understood, disturbances within the prostate, such as inflammation or cancer, cause PSA to leak into the bloodstream in greater amounts.  Importantly, a  PSA level above 4ng/ml will increase the chance of prostate cancer detection with a biopsy to about 25%.  

The PSA Velocity, or change in PSA over an interval of time, is a method of monitoring men in an early-detection program.  If the PSA is noted to rise more quickly than one would expect in the absence of cancer, further testing may be worthwhile.  Furthermore, when cancer is present, the rate that PSA increases may correlate with the severity of the disease.  Percent-free PSA has been approved by the FDA for the early detection of prostate cancer in men with PSA’s between 4 and 10. Percent-free PSA is one form of PSA that circulates in the blood unbound to other molecules.  For unknown reasons, the Percent-free PSA is lower in men with prostate cancer.

Men with a PSA of less than 2 and a normal digital exam can generally have PSA testing every other year.  When the PSA is between 2 and 4, men should be tested each year.  A biopsy of the prostate may be recommended for:  PSA greater than 4; PSA less than 4 but with a greater than normal PSA velocity; a low Percent-free PSA; family history of prostate cancer and a PSA greater than 2.5 in younger men.

 

 

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