Using an ELISA kit that measures the presence of all isoforms of MT1, we found that serum levels of MT1 significantly increased in the serum of patients with HCC treated with sorafenib (median value before sorafenib: 1225 pg/mL; median value after sorafenib: 1353 pg/mL, p < 0.05 using paired Wilcoxon test). Here, MT1M is linked to hepatocellular carcinoma.