Helicobacter pylori, or H pylori, is a bug (bacteria) that infects the lining of the stomach. Studies have shown that infection with H pylori can increase the risk of developing stomach cancer by two to three times the average. But, most people who are infected with H pylori do not go onto develop stomach cancer.

H pylori infection is common. Between 3 and 4 out of every 10 people (30 - 40%) in Britain are infected,at some time in their lives. But only about 3 out of every 100 people (3%) develop stomach cancer in their lifetime. So there must be other reasons why some people develop stomach cancer and others don't. No-one knows for sure what they are. Doctors think a number of risk factors for stomach cancer may interact to cause it, such as

• a diet low in fruit and vegetables
• tobacco smoking
• H pylori infection.

There are different types of stomach cancer. H pylori is more closely linked to some than others. The strongest links are with adenocarcinomas of the stomach and lymphomas of the stomach, also known as MALT lymphomas.

H pylori infection can be detected by a blood test or breath test. Treatment with antibiotics can clear the infection.

H pylori is not routinely tested for and treated. There are a number of reasons for this:

• Most people with H pylori do not get stomach cancer.
• There is no proof that clearing H pylori reduces the risk of stomach cancer
• H pylori infection is very common, so being reinfected with the bug after treatment is common.
• H pylori infection may reduce the risk of cancer of the gullet (oesophagus).

For these reasons doctors usually only test for and treat H pylori infection if a person has symptoms of a stomach ulcer, such as stomach pains.

References:

• Harris A, Misiewicz JJ. Management of Helicobacter pylori infection. BMJ 2001;323;1047-1050.
• SIGN guidelines Management of oesophageal and gastric cancer. 2006 A national clinical guideline.