Scientists say they may be one step closer to detecting the cause of the mystery rise in colon cancer in young people.
Researchers have discovered that people with an aggressive form of the disease have unusually high levels of three bacteria in the gut.
Fusobacterium, Clostridium and Shewanella can become more common because of a diet high in processed foods and low in fiber.
Testing for these three bacteria could help diagnose those most at risk, the authors wrote. It comes as colon cancer diagnoses in under-50s reaches epidemic levels.
The above graph shows colon cancer cases among under 50s by year. There is a drop in 2020 because the Covid pandemic led to fewer people coming forward for screenings
Tests on stool samples from 94 colon cancer patients, showed that among the 24 with the KRAS mutation — behind 40 percent of cases and which causes more fast-growing disease — these bacteria were more common.
The bacteria have been linked to diets high in processed foods — like frozen meals, fast foods and deli meats — and low in fiber, as well as those containing more fats and red meats.
Fusobacteriums can cause inflammation in the gut, the researchers warned, while Colstridium — such as C. difficile — can release toxins.
These raise the risk of damage to DNA in cells, which increases the chance that they could turn cancerous.
For Shewanella, this bacteria proliferates on the surface of tumors, the team said — helping to support their growth.
Colon cancer is surging among under-50s, with cases of the disease rising 50 percent over two decades to nearly 18,000 per year.
It has also become the number one cause of cancer deaths among men in the age group and the number two cause among women.
For comparison, back in 1999 colon cancer was the fourth biggest cancer killer among under-50s and triggered 12,000 cases a year.
Scientists are stumped as to the cause of the rise, but have blamed everything from antibiotics overuse to obesity and even a specific type of fungus.
A $25million global probe has also been launched to attempt to track down the cause of the uptick.
Revealing the study, Dr Weizhong Tang said: ‘Our new work contributes to the growing body of evidence highlighting the significance of microbiota-driven mechanisms in cancer pathogenesis.
‘Understanding the specific associations between different types of KRAS mutations and colon cancer is vital.’
In the paper, published in Microbiology Spectrum, the scientists also found that Bifidobacteriums — linked to consumption of garlic, leeks and onions — could help to prevent the progression of colon cancer.
In the paper, the researchers also tried to make a machine learning model that could use information to help guide personalized treatment recommendations.
But it did not work, with the team saying a larger sample size was required.
A study from 2021 revealed that Fusobacteriums were more common in colon cancer patients who had higher intake of processed foods and red meats and lower intakes of fiber.
