The % year changes of serum OPG (P = 0.001), PTHrP (P = 0.011), tP1NP (P = 0.002), and β-CTx (P = 0.027) in patients with bone metastasis were significantly higher than those in patients without bone metastasis, but there was no significant difference in serum CaN or IL-6 (Fig. 6B). Here, IL6 is linked to bone metastasis.