Prostate specific antigen

In medicine, prostate specific antigen (PSA) is a "glycoprotein that is a kallikrein-like serine proteinase and an esterase, produced by epithelial cells of both normal and malignant prostate tissue. It is an important marker for the diagnosis of prostate cancer."

Abnormal PSA results may revert to normal, although the meaning of this reversion is not clear.