Can prostate-specific antigen levels predict bone scan evidence of metastases in newly diagnosed prostate cancer?

Abstract

Staging in prostate cancer, as in any other cancer has significant ramifications in management. Currently, prostate-specific antigen (PSA) determination and the bone scan are two important procedures in the pretreatment staging workup of prostate cancer. PSA is a very useful serum tumor marker in the management of prostate cancer patients. We retrospectively evaluated 90 patients at the time of initial diagnosis of prostate cancer, all of whom had initial PSA levels measured, as well as bone scans obtained. In addition to the PSA level, we considered clinical stage and pathologic grade in the prediction of bone scan for metastases, at the time of initial diagnosis of prostate cancer. Negative predictive value for PSA values < 10 ng/ml (27 patients), clinical stage A (9 patients) and pathologic grade 1 (19 patients) was 100%. The number of patients with bone scan evidence of metastasis with < 10 ng/ml and > 10 ng/ml PSA levels were 0% (0/27 patients) and 27% (17/63 patients) (p = .0022 [Fisher's Exact test]; p = .003 [chi-square test]). In patients with higher stage (p = .688), grade (p = .039), or PSA levels (p = .0001), the incidence of bone metastases increased. However, none of these three parameters can predict reliably bone scan evidence of metastases (i.e., positive predictive value). The negative predictive values did not improve when a combination of the two or three of the above parameters were used.