Prostate-specific antigen as a marker of bone metastasis in patients with prostate cancer

Objective: Staging in patients with newly diagnosed untreated cancer of the prostate has significant ramifications on the management of the disease. Currently measurement of the serum prostate-specific antigen (PSA) concentration and radionuclide bone scan are two important procedures in the metastatic workup of these patients. We retrospectively evaluated the efficacy of PSA as a staging marker to discriminate prostate cancer patients with bone metastases from those without bone metastases. Materials and Methods: In a retrospective study 158 prostate cancer patients with (n = 21) and without (n = 137) bone metastases were analyzed. In all patients the initial PSA measurement as well as the radionuclide bone scan were evaluated. Results: Patients with bone metastases demonstrated a median serum PSA concentration of 151 ng/ml and only 1 patient revealed a serum PSA concentration of <10 ng/ml. This resulted in a negative predictive value of 98%. In addition 67% of these patients demonstrated a serum PSA concentration of >100 ng/ml, which resulted in a positive predictive value of 74% and an overall accuracy of 92%. Conclusion: The serum PSA concentration seems to provide useful information with regard to the presence of bone metastasis in patients with newly diagnosed cancer of the prostate. A serum PSA value of <10 ng/ml nearly excludes bone metastases, whereas a serum PSA value of >100 ng/ml is highly predictive of bone metastases.