Previous studies have shown that MT expression is upregulated in breast cancer, nasopharyngeal cancer, ovarian cancer, urinary bladder cancer, and melanoma [20–24], while in other cancers, such as hepatocellular carcinoma, prostate cancer, and papillary thyroid carcinoma, MT expression is downregulated [7, 25, 26]. The gene discussed is MCAT; the disease is thyroid gland papillary carcinoma.