Predictive value of serum bone sialoprotein and prostate-specific antigen doubling time in patients with bone metastasis of prostate cancer.

This study aimed to evaluate the diagnostic and prognostic significance of serum bone sialoprotein (BSP) and prostate-specific antigen doubling time (PSADT) in patients with bone metastasis (BM) from prostate cancer (PC). A total of 116 patients with PC, 120 patients with benign prostatic hyperplasia (BPH) and 120 healthy controls were enrolled in this study. PC patients were divided into bone metastasis (BM) group (n=56) and non-bone metastasis (NBM) group (n=60). Serum BSP was detected by Sandwich ELISA. Severity of bone pain was evaluated using visual analogue score (VAS). Serum f-PSA and t-PSA levels were measured by using electrochemiluminescence immunoassay (ECLIA). PSADT was calculated according to the formula: PSADT=lg(2)/[log(PSA2)-log(PSA1)]. The mean serum BSP level in PC patients with BM was significantly higher than in PC patients without BM, BPH patients and controls (P<0.001 for all). Pearson's analysis showed that serum BSP level was positively correlated with VAS in PC patients with BM (P<0.05). Receiver operating characteristics (ROC) analysis demonstrated that BSP discriminated patients with BM from those without BM at the cutoff value of 33.26 ng/mL. The sensitivity and specificity were 78.21% and 79.28%, respectively. The optimal cutoff value of PSADT was 131 days, with sensitivity of 85.69% and specificity of 85.36%. Kaplan-Meier analysis revealed that subjects with higher BSP levels/shorter PSADT had a shorter BM-free period than those with lower BSP levels/longer PSADT. Serum BSP and PSADT are useful biomarkers for the diagnosis of BM from PC, and can be regarded as independent factors for predicting the prognosis of BM from PC. Combined determination of BSP and PSADT can improve accuracy and positive rate of BM from PC significantly.