Oesophageal cancer - Causes of oesophageal cancer

Although the exact cause of oesophageal cancer is not known, certain factors are thought to increase the risk of it developing.

Cancer

Cancer begins with an alteration to the structure of the deoxyribonucleic acid (DNA) found in all human cells. This is known as a genetic mutation. The DNA provides the cells with a basic set of instructions, such as when to grow and reproduce.

The mutation in the DNA changes these instructions so that cells carry on growing. This causes the cells to reproduce in an uncontrollable manner, producing a lump of tissue known as a tumour.

How cancer spreads

Most cancers grow and spread to other parts of the body via the lymphatic system. The lymphatic system is a series of glands (or nodes) located throughout your body in a similar way to your blood circulation system. The lymph glands produce many of the specialised cells needed by your immune system (the body's natural defence against disease and infection).

Left untreated, oesophageal cancer spreads through the outer lining of the oesophagus and into nearby organs such as the liver, lungs or stomach.

Medical conditions

Several medical conditions are thought to increase your risk of oesophageal cancer. These include:

• gastro-oesophageal reflux disease (GORD) – see below
• Barrett's oesophagus – see below
• achalasia – where your gullet loses the ability to move food along, leading to vomiting and acid reflux
• Plummer Vinson syndrome – a rare condition which causes iron deficiency anaemia and small growths in the throat 
• tylosis – a very rare, inherited skin condition

Gastro-oesophageal reflux disease (GORD)

A valve known as a cardiac sphincter is located between your stomach and oesophagus. The valve usually only opens when food is ready to pass from your oesophagus into your stomach.

Sometimes the valve becomes weakened, or it relaxes at the wrong time. This condition is known as gastro-oesophageal reflux disease (GORD).

If you have GORD, stomach acid is able to travel up into your oesophagus. When this happens it causes heartburn, a form of indigestion that causes pain in the front of your chest.

However, it should be stressed that the risk of developing oesophageal cancer from GORD is very small, and most people with GORD will not go on to develop cancer.

Barrett's oesophagus

If you have chronic acid reflux it can sometimes lead to you developing another condition called Barrett's oesophagus. Barrett's oesophagus causes new cells that are very similar to stomach cells to develop in the lower oesophagus. These abnormal cells are resistant to stomach acid but are more likely to become malignant in the future.

Approximately one person out of 11 who has chronic acid reflux goes on to develop Barrett's oesophagus. You are more at risk if you have had chronic acid reflux for a prolonged period of time. About one person in 860 with Barrett's oesophagus develops cancer of the oesophagus.

Other risk factors

Exactly what causes oesophageal cancer to develop is uncertain. However, it appears that repeated and prolonged exposure of the lining of the oesophagus to toxic substances is a significant risk factor.

Risk factors may include:

• regularly smoking and drinking alcohol
• poor diet and obesity
• exposure to chemicals and pollutants

These are explained in detail below.

Alcohol

Drinking too much alcohol increases your risk of developing a number of illnesses and conditions, including cancer of the oesophagus. Long-term heavy drinking causes irritation and inflammation in the lining of the oesophagus. If the cells in the lining of your gullet become inflamed, they are more likely to become malignant (cancerous).

Read more information about alcohol and drinking, including tips on cutting down.

Smoking

Using any form of tobacco (including cigarettes, cigars, pipes and chewing tobacco) will increase your risk of developing cancer of the oesophagus.

When you smoke tobacco you always swallow some of the smoke, which contains many harmful toxins and chemicals. These substances irritate the cells that make up the lining of the oesophagus, which increases the likelihood that they will become malignant.

The longer you smoke, the greater your risk of developing oesophageal cancer.

Read more information about getting help to stop smoking.

Obesity

If you are severely overweight, your risk of developing cancer of the oesophagus is approximately double compared with people with a healthy weight for their height. This may be because obese people are more at risk of developing Barrett's oesophagus (see above).

Diet

A diet low in fruit and vegetables or lacking in vitamins A, C, B1 or zinc has been shown to increase the risk of cancer of the oesophagus. If you eat a healthy, balanced diet you will usually get enough vitamins and zinc in your diet naturally.

Cancer of the oesophagus is much more common in the Far East and Central Asia. It is thought that this may be partly due to the type of diet in these countries, which includes far fewer uncooked vegetables than the western diet. It may also be due to environmental factors.

Read more information about eating a healthy diet.

Chemicals and pollutants

Long-term exposure to chemicals and pollutants may irritate your oesophagus, particularly if you inhale these substances. Chemicals and pollutants known to increase the risk of oesophageal cancer include:

• soot
• metal dust
• vehicle exhaust fumes
• lye (a chemical found in strong industrial and household cleaners)
• silica dust (which comes from materials such as sandstone, granite and slate)

If you have to work with these substances as part of your job, make sure you take all the necessary health and safety precautions. This should help to minimise your exposure to these potentially harmful substances.

Information and advice about health and safety at work can be found on the Health and Safety Executive website.

Want to know more?

• Preventing oesophageal cancer
• Cancer Research UK: risks and causes of oesophageal cancer
• Macmillan: causes of oesophageal cancer