Prostate-specific antigen (PSA). A tissue-specific and sensitive tumor marker

Abstract

Noninvasive methods for the diagnosis of prostatic cancer, its staging and evaluation of response to therapy are often not sufficiently sensitive or specific. Prostate-specific antigen (PSA) was identified in 1979 and has been evaluated since then as a marker, both at the serum and the tissue level. A review is presented in this article. PSA is an organ-specific glycoprotein presented in most prostatic carcinomas, but also in normal prostatic tissue and in benign prostatic hypertrophy (BPH). The monitoring of serum PSA concentrations by serial measurement can be used for the detection of residual or recurrent tumor after primary treatment and for the evaluation of response to systemic treatment of advanced disease. At the tissue level immunohistochemical detection of PSA may help to identify metastatic tumor of unknown origin. PSA serum assays have not been sufficiently sensitive and specific for staging of the primary tumor or for screening purposes. PSA is an equally specific, but more sensitive marker of prostatic carcinoma compared to prostatic acid phosphatase.