The value of serum carboxyterminal propeptide of type 1 procollagen in predicting bone metastases in prostate cancer

Purpose: Carboxyterminal propeptide of type 1 procollagen (P1CP) is believed to be a marker of new bone formation. We investigated the possible application of serum PICP as a biochemical marker for bone metastases in patients with prostate cancer. Materials and Methods: Prostate specific antigen (PSA), prostatic acid phosphatase (PAP), P1CP and alkaline phosphatase were measured in 136 serum samples from 79 patients with untreated prostate cancer, 29 with stage D2 disease in remission and 28 with progressive stage D2 carcinoma. Results: Serum P1CP and alkaline phosphatase were significantly elevated in untreated patients with a positive bone scan (278.9 ± 61.9 ng./ml. and 826.5 ± 176.3 international units per l., respectively) compared to those with a negative bone scan (104.2 ± 4.2 and 200.8 ± 9.1, respectively, p <0.05). The areas under receiver operating characteristics curves were 0.86 for P1CP, 0.87 for alkaline phosphatase, 0.88 for PSA and 0.85 for PAP. The best accuracy rates for P1CP, alkaline phosphatase, PSA and PAP to predict bone lesions were 84, 87, 86 and 84%, respectively. P1CP provided a greater specificity and positive predictive value. These serum markers correlated significantly with the extent of disease on bone scan (p <0.05). The incidence of positive serum P1CP and alkaline phosphatase decreased significantly in response to endocrine therapy in patients with bone metastasis, and increased progressively in association with progression of the tumor (p <0.05) parallel to PSA and PAP. Conclusions: These findings suggest that serum P1CP is a useful indicator for predicting bone metastases.