Oesophageal cancer. Coloured computed Tomography (CT) scan of an axial section through the human thorax, showing oesophageal cancer. At lower centre is a vertebral bone of the spine (black); at upper centre (red) is the heart. Between the heart and spine (green) is rounded diffuse tissue of the oesophagus. Here, the oesophagus is swollen with malignant tumours. Most oesophageal cancers are squamous carcinomas, which may grow to cause difficulty in swallowing. Smoking and drinking alcohol are potential causes. Oesophageal cancer has a poor prognosis; by the time it is detected it has usually spread to other parts of the body.