Esophageal cancer typically begins in the inner layer of the esophagus, and can occur anywhere along the length of the 10-inch tube. It is classified according to the types of cells in which it originates:

• Squamous cell or epidermoid carcinoma. Develops in the thin, flat squamous cells that line the esophagus. This cancer can appear anywhere along the esophagus, but most often develops in the upper and middle part of the esophagus. It is the most common esophageal cancer in African-Americans and the most common esophageal cancer throughout the world.
  
  
• Adenocarcinoma. Develops in glandular (secretory) cells in the lower esophagus near the stomach. Glandular cells produce and release fluids such as mucus. It is more common in whites than in African-Americans. The incidence of adenocarcinoma is the fastest-growing among esophageal cancers in the United States. Approximately two-thirds of esophageal cancers diagnosed now fall into this category, according to the American Cancer Society (ACS). Experts attribute this growth to the rapid rise of acid reflux disease.
  
  
• Other forms. Although less common, other forms of esophageal cancer include:
  
  
• Sarcoma. A malignant tumor arising from connective tissues or muscle.
  
  
• Lymphoma. A malignant tumor that arises in the lymph nodes or in other lymphoid tissue.
  
  
• Small cell carcinoma. A highly malignant carcinoma composed of small round or egg-shaped cells with little cytoplasm.
  
  
• Spindle cell carcinoma. A carcinoma composed of elongated cells. It is frequently a poorly differentiated squamous cell carcinoma.

Cancer that starts in the breast or lung can also spread (metastasize) through the blood stream or lymph system or by direct extension to the esophagus.