Comparison of markers of bone formation and resorption in prostate cancer patients to predict bone metastasis.

We investigated the usefulness of two biochemical markers of bone formation (PICP, the carboxy-terminal propeptide of type I procollagen, and bone ALP, bone-derived alkaline phosphatase) and a marker of bone resorption (ICTP, the carboxy-terminal telopeptide of type I collagen), to determine whether the presence of bone metastasis in prostate cancer could be evaluated and the extent of bone metastasis could be stratified by the serum levels of these markers, compared to total alkaline phosphatase (T-ALP) and prostate-specific antigen (PSA). The serum levels of PICP, bone ALP, ICTP, T-ALP and PSA were significantly higher in patients with both prostate cancer and bone metastasis (n=49) than in patients with benign prostatic hyperplasia (n=35) and patients with prostate cancer without bone metastasis (n=70). The superiority of a marker in the rate of detection of bone metastasis was evaluated with receiver operating characteristic curves. The serum marker levels were compared as a function of metastatic burden in bone (i.e., the extent of disease, EOD grade). We found that bone ALP is the most suitable marker for evaluating bone metastasis, especially for stratifying the degree of bone metastasis. Both PICP and ICTP were useful in this respect, but rather inferior to bone ALP. T-ALP had the lowest ability for detecting bone metastasis, but its correlation with the EOD grade was excellent, second to that of bone ALP. PSA showed limited reliability for stratifying the extent of bone metastasis.