Prostate-specific antigen (PSA) is a protein that is secreted by the cells of the prostate gland and is found in semen, the medium that carries sperm. PSA is the substance that liquefies semen, ...
Credit: Getty Images In men with a total PSA of 2 ng/mL or more, a low percent-free PSA value is associated with a greater likelihood of clinically significant prostate cancer. Adding percent-free PSA ...