Trace elements are required, but these trace elements are also related to cancer, Various malignant neoplasms of different organs are often seen in idiopathic hemochromatosis, but liver cancer is an especially common complication.3) The mechanisms of the hepatocarcinogenesis are thought to be that iron bound to low-molecular protein in the liver generates hydroxyl radicals via the Fenton reaction that damage DNA, and a direct action of iron on the replication process of the DNA. In a study of iron deposits in the surrounding liver parenchyma in a group of HCV-positive liver cirrhosis patients with liver cancer and a group without liver cancer, the iron deposits were reported to be clearly more common in the group with liver cancer.4) 2. Copper Accumulation of large amounts of copper and iron has been reported in the liver and spleen of patients with cancer of the respiratory tract, urinary tract, and thorax,5) and the copper content of benign tumors of the esophagus, bronchi, therefore trace elements are considered one reason for cancer,what are the possible reasons for cancer?