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Bacteria rule our bodies –microbes in the stomach linked to cancer

We’re at the mercy of our microbial overlords – at least that’s what more and more scientific evidence seems to be suggesting. Alzheimer’s disease, autism, diabetes and cancer are just some of the conditions that appear to be linked to the ecosystem of bacteria that live inside our bodies. There’s even new evidence that “a mysterious bacterium found in up to half of all colon tumours also travels with the cancer as it spreads”.

New research, led by Worldwide Cancer Research scientist Professor Ceu Figueiredo at the University of Porto in Portugal, has now found that the diversity and abundance of specific types of bacteria living in the stomach differs dramatically between people that have stomach cancer and those that suffer from a condition that causes inflammation of the stomach lining (called chronic gastritis).

“Bacteria in the stomach may increase the risk of cancer by producing chemicals that cause damage to the DNA of human cells” said Figueiredo. “Bacteria can also send out molecular signals to nearby human cells that cause inflammation in the stomach, or send signals for the human cells to divide, thereby increasing the risk of stomach cells to acquire harmful genetic mutations that are important in cancer development and progression.”

There are around one million new cases of stomach cancer diagnosed each year and it is well documented that one bacteria in particular, called Helicobacter pylori, plays a crucial role in the early stages of cancer development. As H. pylori grows and colonises the stomach lining, the amount of acid secreted into the stomach drops. This change in acidity could allow different types of bacteria to become more prominent in the stomach.

“We saw that the stomach cancer microbial community shifts in diversity and abundance from gastritis to cancer, which are both linked to H. pylori infection. We were also able to reveal that the stomach microbiome in people with cancer is ‘dysbiotic’ – meaning that the imbalance or shift in bacterial diversity could be harmful” explained Figueiredo. This imbalance is essentially a bacterial signature that could be alerting to the presence of cancer. “A future perspective could be to use microbial dysbiosis as a way to manage patients with stomach precancerous lesions more accurately, but further studies are needed to clinically validate any such use”.

So what’s next for Figueiredo and her research? “Our study involved analysis of 173 patients with stomach cancer or chronic gastritis so we really need to validate our findings in larger populations. We are also very keen to see how the stomach microbiome changes throughout progression of the disease, which would allow us to gain insight into the mechanisms that lead to gastric cancer development and progression. This information will be extremely useful for developing effective strategies to prevent and treat stomach cancer at the earliest stage.”

The full research article is freely available to read here: http://gut.bmj.com/content/early/2017/11/03/gutjnl-2017-314205

Image credit: AJC1 - Flickr

Science Communications Manager

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