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

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.

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.

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%.

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.