VALUE OF PROSTATE-SPECIFIC ANTIGEN AS A TUMOR-MARKER

Prostate-specific antigen (PSA) is the most important tumor marker for prostate cancer. However, the diagnostic limits of PSA have to be tak en into consideration because PSA is also secreted by normal prostate tissue and, with benign prostatic hyperplasia, false positives are pos sible. Although there is a direct correlation between the serum PSA co ncentration and the clinical stage of the tumor, PSA is not sufficient ly reliable to determine the stage of the disease on an individual bas is. Low serum PSA concentrations (less than 20 ng/ml) in patients with previously untreated prostate cancer seem to be predictive for a nega tive bone scan. Serum PSA values also reflect the prognosis of the pat ient. With respect to monitoring patients after definitive therapy, PS A is a very sensitive tumor marker. However, in a small number of pati ents PSA-negative tumor recurrences occur.