The exact cause of oesophageal cancer is unknown, but certain things can increase the risk of it developing.
Gastro-oesophageal reflux disease (GORD) is where a weakness in the muscles above the stomach means stomach acid can travel up into the oesophagus.
In around 1 in 10 people with GORD, repeated damage from stomach acid over many years can eventually cause changes in the cells lining the oesophagus. This is called Barrett's oesophagus.
These abnormal cells are at an increased risk of becoming cancerous in the future, although the risk is still small.
Between 1 and 5 people out of 100 (1 to 5%) with Barrett's oesophagus will go on to get oesophageal cancer.
Drinking too much alcohol irritates and inflames the lining of the oesophagus.
If the cells in the lining of your gullet become inflamed, they're more likely to become cancerous.
Read more about alcohol and drinking, including tips on cutting down.
Tobacco smoke 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'll become cancerous.
The longer you smoke, the greater your risk of developing oesophageal cancer.
If you're overweight, your risk of developing cancer of the oesophagus is higher than people of a healthy weight.
The more overweight you are, the higher the risk.
This may be partly because overweight people are more at risk of long-term acid reflux.
Not eating enough fruit and vegetables may increase your risk of getting oesophageal cancer.
Aim to eat at least 5 portions of fresh fruit and vegetables every day.
Other medical conditions
Certain rare medical conditions can also increase your chances of getting cancer of the oesophagus.