The gullet (oesophagus)

The oesophagus (pronounced e-sof-fa-gus), is also known as the gullet. It is a long, muscular tube that connects your throat to your stomach. It is at least 12 inches (30cm) long in adults. When you swallow food it is carried down the oesophagus to the stomach, and the walls of the oesophagus contract to move the food down.

At the upper part of the oesophagus it runs behind, but is separate from, the windpipe (trachea). The windpipe connects your mouth and nose with your lungs, enabling you to breathe.

The digestive system

Various lymph nodes (which filter fluid and can trap bacteria, viruses and cancer cells) are near the oesophagus; in your neck, in the middle of your chest and near the area where the oesophagus joins the stomach. A tumour can occur anywhere along the length of the oesophagus.

What is cancer?

The organs and tissues of the body are made up of tiny building blocks called cells. Cancer is a disease of these cells.

Cells in different parts of the body may look and work differently but most reproduce themselves in the same way. Cells are constantly becoming old and dying, and new cells are produced to replace them. Normally, cells divide in an orderly and controlled manner. If for some reason the process gets out of control, the cells carry on dividing, developing into a lump which is called a tumour.

Tumours can be either benign or malignant. Cancer is the name given to a malignant tumour. Doctors can tell if a tumour is benign or malignant by examining a small sample of cells under a microscope. This is called a biopsy.

In a benign tumour the cells do not spread to other parts of the body and so are not cancerous. However, if they continue to grow at the original site, they may cause a problem by pressing on the surrounding organs.

A malignant tumour consists of cancer cells that have the ability to spread beyond the original area. If the tumour is left untreated, it may spread into and destroy surrounding tissue. Sometimes cells break away from the original (primary) cancer. They may spread to other organs in the body through the bloodstream or lymphatic system.

The lymphatic system is part of the immune system - the body's natural defence against infection and disease. It is a complex system made up of organs, such as bone marrow, the thymus, the spleen, and lymph nodes. The lymph nodes (or glands) throughout the body are connected by a network of tiny lymphatic ducts.

When the cancer cells reach a new area they may go on dividing and form a new tumour. This is known as a secondary cancer or metastasis.

It is important to realise that cancer is not a single disease with a single type of treatment. There are more than 200 different kinds of cancer, each with its own name and treatment.

Types of cancer

Carcinomas

The majority of cancers, about 85% (85 in a 100), are carcinomas. They start in the epithelium, which is the covering (or lining) of organs and of the body (the skin). The common forms of breast, lung, prostate and bowel cancer are all carcinomas.

Carcinomas are named after the type of epithelial cell that they started in and the part of the body that is affected. There are four different types of epithelial cells:

• squamous cells - that line different parts of the body, such as the mouth, gullet (oesophagus), and the airways
• adeno cells - form the lining of all the glands in the body and can be found in organs such as the stomach, ovaries, kidneys and prostate
• transitional cells - are only found in the lining of the bladder and parts of the urinary system
• basal cells - that are found in one of the layers of the skin.

A cancer that starts in squamous cells is called a squamous cell carcinoma. A cancer that starts in glandular cells is called an adenocarcinoma. Cancers that start in transitional cells are transitional cell carcinomas, and those that start in basal cells are basal cell carcinomas.

Leukaemias and lymphomas

These occur in the tissues where white blood cells (which fight infection in the body) are formed, i.e. the bone marrow and lymphatic system. Leukaemia and lymphoma are quite rare and make up about 6.5% (6.5 in 100) of all cancers.

Sarcomas

Sarcomas are very rare. They are a group of cancers that form in the connective or supportive tissues of the body such as muscle, bone and fatty tissue. They account for less than 1% (1 in 100) of cancers.

Sarcomas are split into two main types:

• bone sarcomas - that are found in the bones
• soft tissue sarcomas - that develop in the other supportive tissues of the body.

Others forms of cancer

Brain tumours and other very rare forms of cancer make up the remainder of cancers.

Causes of oesophageal cancer

Each year, nearly 7600 people in the UK are diagnosed with cancer of the oesophagus. It is becoming more common in Europe and North America. Men are affected more than women and it occurs generally in older people.

There are two types: squamous cell carcinoma and oesophageal cancer (which is known as adenocarcinoma). The causes are unknown, but cancer of the oesophagus would appear to be more common in people who have long-term acid reflux (backflow of stomach acid into the oesophagus). Damage to the oesophagus caused by acid reflux is known as Barrett's oesophagus.

Barrett's oesophagus is a condition where abnormal cells develop in the lining of the lower end of the oesophagus. It is not a cancer, but over a long period of time a small number of people with this condition (around 1 in 100) may develop a cancer of the oesophagus.

Cancer of the oesophagus is more commonly seen in some populations in the Far East and Central Asia, which suggests that diet, or the environment, may affect its development. Squamous cell carcinoma is more common among smokers and people who drink a lot of alcohol (especially spirits) or have a poor diet.

Other conditions affecting the oesophagus, such as achalasia, may also very occasionally lead to cancer. Achalasia is where the muscle that controls the opening between the oesophagus and the stomach does not relax properly. This makes food build up in the oesophagus and stops it emptying into the stomach.

In most people, cancer of the oesophagus is not caused by an inherited faulty gene, and so other members of your family are not likely to be at risk of developing it. However, a very small number of people who have a rare inherited skin condition known as tylosis may develop oesophageal cancer.