H. pylori and cancer

Microscope image of helicobacter pylori bacterium

Infection with Helicobacter pylori (H. pylori) increases the risk of stomach cancer. But for most people, carrying H. pylori will not cause them any problems.

What is H. pylori?

Helicobacter pylori (H. pylori) is a type of bacteria. It infects the lining of the stomach.  It normally infects people during childhood and is spread through contaminated food and water. H pylori infection used to be very common, but is now becoming much less so in developed countries such as the UK.

Once infected, a person usually stays infected for life unless they are treated with specific antibiotics. Normally, the infection won't cause a person any problems at all. But in some people, H. pylori can cause stomach ulcers, and more rarely, stomach cancer.

What cancers are linked to H. pylori?

H. pylori can cause stomach cancer (especially a type called non-cardia gastric cancer). While most people won't have any problems from an H. pylori infection, more than 4 in 10 stomach cancer cases in the UK are caused by these bacteria.

About 3 in 100 cases of Non-Hodgkin Lymphoma in the UK are caused by H. pylori as well. And there is some evidence that bowel cancer risk may also be increased in people with H. pylori infection.

H. Pylori has also been also linked to a reduced risk of oesophageal (food pipe) cancer. It’s unclear why this is the case.

As H. Pylori infection rates have gone down in the UK, stomach cancer rates have dropped, but oesophageal cancer rates have risen. This is probably due in part to changing levels of H. pylori, but changes in other risk factors like smoking would have also had an effect

How can H. pylori cause cancer?

H. pylori can cause long-lasting inflammation in the stomach (called ‘severe chronic atrophic gastritis’ or SCAG) and this can lead to stomach cancer. People with SCAG have an increased risk of stomach cancer.

But millions of people around the world are infected with these bacteria and only very few (1-3 out of 100) go on to develop stomach cancer. Researchers think this is because some types of H. Pylori are more likely to cause problems than others. And other risk factors such as smoking and what we eat can also affect our risk.

How H. pylori may cause other types of cancer, including bowel cancer, is less well understood at the moment and more research is needed.

Reducing the risk

H. pylori infection can be detected with a blood test or a breath test. If you're worried that you might have an H. pylori infection, speak to your doctor. It can usually be cured with a course of antibiotic treatment.

Treating H. pylori infection can reduce the risk of stomach cancer. But having the infection could lower the risk of oesophageal cancer. So treating H. pylori infection might not be beneficial unless you have symptoms, such as stomach pain.

In the UK, other ways to reduce stomach cancer risk are likely to have a bigger impact than treating H. pylori. This includes giving up smoking and eating a healthy, balanced diet.

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