[Metastasis and markers].

Tumor markers are antigens which can be associated with certain malignancies. A variety of markers have been demonstrated in genitourinary tumors. The best known examples are human chorionic gonadotropin (bHCG) and alpha-fetoprotein (AFP) for testicular tumors, prostatic acid phosphatase (PAP) and prostatic specific antigen (PSA) for prostatic cancer. The plasma levels of these substances are influenced by the tumor mass and therefore by the tumor stage. Markedly elevated plasma levels can be demonstrated when metastases are present, although a few patients without metastases may elaborate abnormal amount of markers. The removal of the primary tumor leads to a fall to normal levels: a still increased level indicates residual primary tumor or the presence of metastases. Measurements of markers are also of value in estimating the effects of medical treatment and in detecting local or distant recurrences.