Imaging 
• A barium swallow and x-ray of the esophagus may reveal a tumor .
• A chest x-ray can detect masses in the midchest area and the lungs.
• CT scans of the whole lung (mediastinum) and abdomen (liver) will define the size and lateral extent of the
  tumor so that the stage can be identified accurately. (CT scans will also highlight lymph nodes , although these 
  may not be cancerous.)
• Esophageal endoscopic ultrasound of the surrounding tissue will assess the size and depth of the tumor's
  invasion of the esophagus and evaluate the status of nearby lymph nodes.

Endoscopy and Biopsy 
• Esophagoscopy is the key test because it allows both visualization and biopsy. A flexible fiber-optic tube is 
  passed through the mouth and down the esophagus. A piece of tissue may be removed with forceps (punch 
  biopsy and cytology). About 25 to 40 percent of patients have a narrowing of the esophagus, which does not 
  permit an endoscope to be passed, so an esophageal dilation may be needed.
• For tumors near the place where the trachea (central air passage) divides into the right and left bronchi, it is 
  advisable to include bronchoscopy .
• A mediastinoscopy (inspection of center of the chest through a thin telescope) may be needed occasionally to 
  assist in staging , for biopsy and to help decide on surgery.