Serum calcium, alkaline phosphotase and hemoglobin as risk factors for bone metastases in bladder cancer

Early detection of bone metastases is helpful for the treatment of bladder cancer (BC). In this study, we investigated the potential risk factors for bone metastasis in newly diagnosed patients with BC. A total of 902 patients diagnosed with BC between January 2000 and August 2016 were retrospectively reviewed. Of these patient, 50 (5.5%) were identified with bone metastasis. The serum levels of alkaline phosphatase (ALP) and calcium were significantly higher in patients with bone metastases than those without bone metastases (P = 0.015 and P<0.001). And the concentration of hemoglobin (HB) was significant lower in bone metastatic patients compared with non bone metastatic patients (P = 0.009). Multivariate logistic regression analysis indicated that ALP, HB and calcium were independent risk factors for bone metastases in patients with BC. The cut off values of ALP, HB and calcium were 116 U/L, 37.5g/L and 2.54 mmol/L according to the receiver operating characteristic (ROC) curves analysis. And combined ALP, HB with calcium had the highest diagnostic accuracy for predicting bone metastases in BC patients (AUC = 0.760, P<0.001). Therefore, for newly diagnosed patients with BC, the concentrations of ALP >116 U/L, HB <37.5 g/Land calcium >2.54 mmol/L were the risk factors for developing bone metastases. Combined ALP, HB with calcium was more useful to diagnose the bone metastases.