IGFBP3 and esophageal cancer: For patients in M category, the OR was 3.270 (95% CI: 1.670–6.400, p = 0.001, Fig. 4), suggesting that for esophageal cancer patients in M category, patients whose tumor cells metastasized to distant organs (beyond regional lymph nodes) had lower IGFBP-3 level than those without distant metastases.