One clinical symptom of esophageal cancer is primarily dysphagia, especially progressive aggravation of dysphagia and difficulty swallowing. When these symptoms occur, the possibility of esophageal cancer should be considered, and one should seek medical attention at a hospital. An esophagoscope examination, which is an endoscopy, should be performed. Usually, under endoscopy, morphological changes in the esophagus can be observed, and if a biopsy is taken and cancer cells are found, esophageal cancer can be diagnosed. Therefore, the primary diagnostic approach for esophageal cancer involves an endoscopic examination and biopsy of the esophageal mass, which is the gold standard for diagnosis. After diagnosis, it is also necessary to perform comprehensive examinations such as chest and full abdominal CT scans, superficial lymph node ultrasound of the whole body, barium meal tests for the esophagus, and other examinations like ultrasound and esophagoscopy to assess the stage of the cancer and decide upon further treatment plans.