Worldwide Cancer Research Menu

What role do bacteria in our stomach play in the development of cancer?

Professors Figueiredo and Machado and their team are studying which types of stomach bacteria might contribute to stomach cancer development.

Around 7,000 people in the UK are diagnosed with stomach cancer every year. Stomach cancer can take decades to develop. In some people long-term infection with a common type of bacteria called Helicobacter pylori (H. pylori) increases stomach cancer risk. Infection leads to the destruction of cells that produce acid, changing the stomach environment and allowing other types of bacteria to grow. The researchers believe these different bacteria might also contribute to stomach cancer development, and in this project they want to find out if they are right.

The team will study the type of bacteria found in the stomachs of different people who are at different stages- from healthy to those with stomach cancer. They hope that by defining the types of bacteria besides H. pylori which live in the stomach under these changing conditions, their work will help lead to novel strategies to stop stomach cancer.

Investigating how stomach cancer begins and how to stop it

Despite the progress being made in cancer research, stomach cancer is still one of the cancers with a low survival rate. In 2008 almost 990,000 people around the world were diagnosed with stomach cancer and 738,000 people died from the disease. Stomach cancer is strongly linked to prolonged inflammation of the lining of the stomach and changes in the bacteria found there. Professor Andrew Giraud is investigating the role a molecule called IL-11 plays in stomach cancer. He will be using mice models which mimic one of the early events preceding human stomach cancer caused by bacteria. A major focus of this work will not only be to understand how cancer begins, but to identify potential ways to stop the process. He hopes to take it further and find small molecules which could actually prevent stomach cancer occurring. If successful, and after extensive further research, his findings could potentially be used to try and treat people with stomach cancer.

How does the reduction in stomach acid help progression of cancer?

Stomach cancer is a common and life-threatening disease, which nearly always develops in people who have had a long-term infection with a bacterium called Helicobacter pylori. One of the pre-cancerous stages of the disease is called "atrophy" which destroys some of the acid-producing cells in the stomach. As a result, the pH within the stomach becomes higher than normal, making it less acidic and more alkaline (known as hypochlorhydria). Studies in mice have shown that this elevated pH allows other microorganisms, such as bacteria, to start growing in the stomach, where they would not normally survive. It is believed that the presence of these bacteria contributes to the development of cancer within the stomach. Curiously, however, long-term use of acid-suppressing drugs does not have the same effect. Professor Pritchard is therefore going to use his new Worldwide Cancer Research grant to study the stomach environment in mice that develop cancer following Helicobacter pylori infection, in the hope that the studies will identify molecules that indicate those people who are more likely to develop cancer. If he identifies such molecules, these could be used to develop a better screening programme for patients who may be at risk of developing stomach cancer.