IBSP and cancer: There is limited evidence that bone turnover markers can be used to predict bone metastases in patients with early-stage malignant tumors, with PINP (N-terminal propeptide of type 1 procollagen), ICTP (carboxyterminal cross-linked telopeptide of type I collagen) and bone sialoprotein (BSP), with tumor immunoexpression of BSP being the most studied and discussed.