Procollagen type I carboxyterminal extension peptide in serum: a reliable marker of bone metastatic disease in newly diagnosed prostate cancer?

Abstract

This study evaluates the accuracy of type I procollagen, a bone matrix glycoprotein, and prostate-specific antigen (PSA) as markers for predicting the results of radionuclide bone scan in newly diagnosed, previously untreated patients with prostate cancer. 74 patients underwent serum PSA and procollagen determination using specific antibodies. A staging radionuclide bone scan was then performed; patients with positive bone scan were submitted to x-rays of the suspicious zones. Then, we calculated sensitivity, specificity, positive predictive value, negative predictive value and overall accuracy of procollagen and PSA in the detection of bone metastases. Procollagen alone had 83.3% sensitivity, 96% specificity, 90.9% positive predictive value, 92.3% negative predictive value and 91.9% overall accuracy. PSA alone had 70.1% sensitivity, 86% specificity, 70.8% positive predictive value, 86% negative predictive value and 81.1% overall accuracy. According to our data, we no longer perform a staging radionuclide bone scan in patients with PSA < 20 ng/ml and normal procollagen level, diminishing the number of radionuclide bone scans and increasing the overall net savings for the health care system.