Multivariate logistic regression analysis indicated that only OPG (P < 0.001), PTHrP (P < 0.001), tP1NP (P = 0.001), and β-CTx (P < 0.001) were independent diagnostic factors for bone metastasis in lung cancer, while CaN and IL-6 were not (Fig. 4A and Supplementary Table 4). The gene discussed is PTHLH; the disease is bone metastasis.