SKELETAL ALKALINE-PHOSPHATASE IN THE METASTATIC - WORK-UP OF PATIENTSWITH PROSTATE-CANCER

Objective: To compare the efficacy of two tests, prostate-specific ant igen (PSA) and skeletal alkaline phosphatase (SAP) as staging markers to discriminate patients with cancer of the prostate (CaP) with bone m etastases (M+) from those without bone metastases (M0). Methods: Thirt y-nine untreated patients with CaP Mo (n = 22) and CaP M+ (n = 17) alo ng with 10 patients with benign prostatic hyperplasia, who served as c ontrols, were entered in this study. Serum concentrations for SAP and PSA were determined using two immunoassays. Receiver operating charact eristic (ROC) curves were constructed to compare the ability of SAP an d PSA to discriminate patients with CaP M+ from CaP M0. Results: None of the M0 patients but 65% of the M+ patients exhibited an SPP value a bove the reference range (<19 ng/ml). A corresponding cutoff point of 100 ng/ml for PSA demonstrated that 27% of M0 patients and only 65% of the M+ patients exhibited a value > 100 ng/ml. This resulted in a sen sitivity of 65% for both markers. However, SAP revealed a higher speci ficity than PSA (100 vs. 73%). The ROC curve comparing SAP and PSA dem onstrated the superiority of SAP as a marker for bone metastases. Conc lusion: Our findings suggest that SAP could become a useful marker in the evaluation of patients with newly diagnosed CaP as it seems to pro vide additional information concerning the skeletal status of these pa tients.