Oesophageal cancer refers to cancer that develops within the oesophagus, the tube that transports food from your throat to your stomach to be digested.

There are three layers of the oesophageal wall, which include the mucosa (made up of squamous cells), submucosa and muscle layer (muscularis propria), in addition to the outer covering (adventitia).

The two most common types of oesophageal cancer are:

• Adenocarcinoma – cancer that develops in the glandular cells which line the oesophagus. This type of cancer typically forms in the lower section of the oesophagus
• Squamous cell carcinoma – cancer which begins in squamous cells that line the oesophagus. This often develops in the middle and upper part of the oesophagus

Other types of oesophageal cancer include small cell carcinoma, lymphoma, neuroendocrine tumours and gastrointestinal stromal tumours.

Oesophageal cancer is the 19^th most common cancer in Singapore, with men more likely than women to develop oesophageal cancer.

Oesophageal cancer can be described in stages depending on how early or advanced the cancer is.

The TNM system is used to stage oesophageal cancer and helps doctors understand what your cancer looks like. TNM stands for:

• Tumour – the degree to which the tumour has affected other tissue.
• Node – is a measure of the extent of lymph node involvement.
• Metastasis – the degree to which the cancer has spread to other organs of the body.

The TNM information, along with other tests helps determine the stage of your oesophageal cancer.

• Stage 0 – the cancer is only in the top layer of the oesophageal lining (epithelium) and has not spread to deeper layers of the oesophagus.
• Stage I – the cancer has grown into the mucosa, submucosa or muscle layer (muscularis propria).
• Stage II – the cancer has spread to the muscularis propria or outer layer of the oesophagus (adventitia). Alternatively, the cancer has grown into the mucosa or submucosa and has spread to one or two nearby lymph nodes.
• Stage III – the cancer has spread to the mucosa, submucosa, adventitia or muscularis propria and no more than six nearby lymph nodes. Alternatively, the cancer has grown into the pleura, pericardium or diaphragm and no more than two nearby lymph nodes.
• Stage IV – the cancer has spread beyond the oesophageal wall to nearby lymph nodes and parts of the body such as the pleura, pericardium, diaphragm, trachea, aorta and spine, or throughout the body to distant lymph nodes and/or organs such as the liver or lungs