Scientists say they may be one step closer to pinpointing the cause of the mysterious rise in bowel cancer among young people.
Researchers have already suggested it could be linked to shifts in the gut microbiota – or bacteria in the gut – that cause mutations in cells.
But now a team in China says a more aggressive form of the disease may be linked to three bacteria in the gut – Fusobacterium, Clostridium and Shewanella – that become more common due to a diet high in processed foods.
Tests on stool samples from 94 colon cancer patients showed that among 24 with the KRAS mutation – responsible for 40 percent of cases and which causes faster-growing diseases – these bacteria were more common.
The graph above shows the cases of colon cancer among those under 50 per year. There has been a decline in 2020 as the Covid pandemic led to fewer people registering for screenings
The bacteria have been linked to diets high in processed foods – such as frozen meals, fast food and processed meats – and low in fiber, as well as diets higher in fats and red meat.
Fusobacteria can cause inflammation in the intestines, the researchers warned, while Colstridium – like C. difficile – can release toxins.
These increase the risk of damage to the DNA in cells, making them more likely to develop cancer.
For Shewanella, this bacteria proliferates on the surface of tumors, the team said – and helps support their growth.
Bowel cancer is increasing among the over-50s, with the number of cases of the disease increasing by 50 percent in twenty years to almost 18,000 per year.
It has also become the leading cause of cancer deaths among men in this age group and the second cause among women.
By comparison, in 1999, colon cancer was the fourth leading cause of cancer death among people in their 50s, causing 12,000 cases per year.
Scientists are baffled as to what’s causing the rise, but have blamed everything from overuse of antibiotics to obesity and even a specific type of fungus.
A $25 million global investigation has also been launched to try to pinpoint the cause of the upturn.
Unveiling the study, Dr Weizhong Tang said: ‘Our new work adds 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 crucial.’
In the newspaper, published in Microbiological spectrumscientists also discovered that Bifidobacteria – linked to the consumption of garlic, leeks and onions – can help prevent the progression of colon cancer.
In the paper, the researchers also attempted to create a machine learning model that could use information to guide personalized treatment recommendations.
But it didn’t work because the team said a larger sample size was needed.
a 2021 study revealed that Fusobacteria were more common in colon cancer patients who had a higher intake of processed foods and red meat and a lower intake of fiber.