The reasons for the earliest formation of esophageal cancer cells and the pattern of metastasis are still not understood. Normal cells of esophageal mucosa proliferate when the body needs them, and die after aging and damage by regulation. It may be in this process that esophageal cells become metabolically dysregulated and proliferate excessively to become cancerous. Theoretically, it is speculated that the esophagus is constantly in close contact with food and influenced by the environment, which has a high probability of genetic alteration of mucosal cells and may lead to rapid overproliferation of a few cells, so that the cells divide and form tiny lumps, which do not die easily even after aging and damage, forming the primary lesion of cancer. Cancer cells usually originate from squamous epithelial or glandular epithelial cells, called squamous carcinoma and adenocarcinoma, respectively. In China, squamous carcinoma of the esophagus is more common. If left untreated, the primary cancer lesion of esophagus will keep increasing, invade the surrounding tissues and organs, and spread to lung, liver, bone, brain and other tissues and organs through blood vessels or lymphatic vessels to form more lesions such as second and third, and this process is metastasis.