Prostate-specific antigen

Prostate specific antigen, abbreviated PSA, is marker that is quite specific for the prostate.

General

• Quantity in the serum used to screen for prostate cancer.
• PSA immunostain useful for classifying a carcinoma as prostate carcinoma.

Serum PSA

• Normal - typically < 4.0 ng/mL.
• Increases with age.

Prostate specific antigen density

• Abbreviated PSAD.

Better predictor than (unadjusted) serum PSA for:

• Gleason score upgrading on prostatectomy.
• BPH versus cancer.

A forumla for PSAD

• Benson et al.:

$PASD={\frac {serumPSA}{volume}}$

• Where:

$volume={\frac {1}{2}}D1xD2xD3$

D1, D2, D3 are the major axes.

Note:

• The volume of an ellipsoid is:

${\frac {4}{3}}\pi D1xD1xD3$

See also

• Prostate cancer.