Serum osteoprotegerin levels are increased in patients with advanced prostate cancer

Purpose: Osteoprotegerin (OPG) is a soluble osteoclastogenesis inhibitor th at regulates bone turnover. We reported recently that OPG protein expressio n is significantly increased in prostate cancer (Cal?) cells present in bon e metastases. The aim of this study was to determine serum OPG levels in pa tients at different stages of CaP and correlate the results with disease st atus. Experimental Design: OPG levels were examined in patients with benign prost atic hyperplasia, clinically localized CaP, early recurrence of CaP, and ad vanced CaP and evidence of bone metastases. Serum OPG levels were measured by sandwich ELISA assays. The serum Crosslaps (sCTX) assay was used to quan tify bone resorption in the advanced Cal? group. Results: Serum OPG levels were increased significantly in the advanced CaP group versus all other groups. There was no significant correlation between serum OPG levels and PSA levels either in the advanced Cal? group or withi n any of three treatment subclasses of this group: no Tx, those not treated ; Tx, those treated; and R, those treated with resorption blockers. Levels of OPG were negatively correlated with sCTX levels only in the advanced Cal ? Tx group. sCTX levels correlated with prostate-specific antigen levels in the advanced Cap Tx and R groups but not in the no-Tx group. Conclusions: Our data show that serum OPG levels are increased with advance d CaP. We hypothesize that OPG levels are related to CaP progression and su ggest that further studies of the biological effects of OPG on CaP metastas es are warranted.