Scientists can predict the onset of colon cancer by looking at your gut bacteria

woman holding gut area in pain, to represent colon cancer sign. (Getty Images)
Your gut could help predict colon cancer. (Getty Images)

Variations in gut bacteria could be key in "predicting" who will develop colon cancer, a new study suggests.

Also known as the gut microbiota, this refers to all the microorganisms living in your gut, which are entirely unique to each person. The human gut is home to as many as more than 100 trillion microorganisms, weighing around 200g (the same as an adult hamster!), charity Guts UK points out.

Researchers have now identified differences in the gut microbiome of people who developed pre-cancerous colonic lesions (a small growth, also known as 'polyps'), indicating a potential connection between gut bacteria and the onset of lesions in the colon and cancers.

Bowel cancer is the general term for cancer that begins in the large bowel. Depending on where it starts, it is sometimes called colon (the first part of the large bowel) or rectal cancer (the last part of the large bowel). It is also known as colorectal cancer.

These findings, presented at United European Gastroenterology (UEG) Week 2023 in Copenhagen, offer potentially life-saving new methods of detection and prevention of colorectal cancer, the second leading cause of all cancer-related deaths across Europe.

Faecalibacterium prausnitzii bacteria, illustration. This is one of the most abundant bacterial species found in the human gut. Its presence is thought to give protection against a number of gut disorders including inflammatory bowel disease, Crohn's disease and colon cancer.
The microorganisms living in your gut weigh around the same as a hamster. (Getty Images)

The study

The team, from the Netherlands, assessed 8,202 participants and linked data from the Dutch Microbiome Project with the Dutch nationwide pathology database to identify all recorded cases of colonic biopsies from the last five decades.

Colorectal cancer develops from pre-cancerous lesions within the gut, making the removal of these lesions important for preventing the disease. But existing, non-invasive detection methods like the 'faecal immunochemical test' (looks for blood in a sample of your poo), produce a high number of false positives, leading to unnecessary colonoscopies (examinations of the colon or rectum).

The researchers analysed the function and composition of the gut microbiomes of those who developed pre-cancerous colorectal lesions before poo sampling in the 15 years between 2000 and 2015, as well as those who developed lesions after sampling between 2015 and 2022.

These groups were then compared with individuals with normal colonoscopy findings and the general population.

To gain a deeper insight into the gut microbiome and what it does, the team also examined specific bacterial strains and their functions within the gut by reconstructing their genomes (a set of DNA) from metagenomic data (metagenomics is used to study a specific community of microorganisms).

The researcher's results revealed that people who developed colonic lesions after poo sampling showed increased diversity in their gut microbiome, in comparison with those who didn't develop lesions.

Further to this, the function of the microbiome and the way it is made up differed among those with pre-existing or future lesions and also varied based on the type of legion.

Specific bacterial species, including Lachnospiraceae and the genera Roseburia and Eubacterium (basically different families of bacteria), were linked with the future development of lesions.

Watch: Keys to improving your gut health

'The gut microbiome could advance early detection of colon cancer'

Dr Ranko Gacesa, the study's lead author from the University Medical Center Groningen in northern Holland, said his team's results show people's gut microbiomes could help advance early detection methods for colorectal cancer.

"While we didn’t investigate mechanisms in this study, it is known from previous research that some of the bacterial species identified may have properties that could contribute to the development of colorectal lesions," Dr Gacesa explains.

"A bacterium called Bacteroides fragilis, for example, is known to produce a toxin that can lead to chronic low-grade inflammation in the gut.

"Prolonged inflammation is believed to be potentially genotoxic and carcinogenic, meaning it may cause genetic damage and promote cancer.

"The connection between the gut microbiome and pre-cancerous lesions has been under-explored, leaving uncertainty about whether gut bacteria can predict the future onset of colorectal cancer.

"Our findings suggest that the microbiome could act as a valuable tool to improve existing tests, advancing early detection methods for pre-cancerous lesions and colorectal cancer."

Additional reporting SWNS.