We then evaluated the ability of blood IGFBP1 levels to distinguish between the patients with metastatic and non‐metastatic tumors by performing receiver operator‐characteristic curve (ROC) analysis, implicating that blood IGFBP1 could potentially be used as a diagnostic biomarker for metastatic lung cancer (Figure S1J, Supporting Information). Here, IGFBP1 is linked to metastatic neoplasm.