Clinically, the staging of esophageal cancer does not only depend on the length of the lesion, but more importantly on the depth of infiltration and whether there is lymph node metastasis or distant metastasis. If the lesion is as long as 7cm, it should be T3 according to the domestic staging standard. If there is indeed no lymph node metastasis, it is stage 2; if there is lymph node metastasis, it is stage 3; if there is distant metastasis, it is stage 4. Different stages have different treatment principles and different prognosis of patients. Therefore, before taking standardized comprehensive treatment for esophageal cancer, comprehensive examination must be conducted to clarify the stage before treatment.