Bowel cancer samples that have been stored for up to 100 years will be analysed by British scientists to try to solve the mysterious rise of the disease in young people.
The BBC reports that while most bowel cancers still being found in older adults, the rise in younger patients is a global phenomenon, including in the UK, where rates have increased by 75% in the under-24s since the early 1990s, baffling scientists.
At St Mark’s in London, The National Bowel Hospital has a unique collection of tens of thousands of archived cancer samples, which are currently undergoing advanced analysis to understand what caused each cancer and what’s changed over the decades.
Science doesn’t appear to have a clear answer. Everything from obesity and ultra-processed foods, to antibiotics and the microbiome, to air pollution and microplastics, has been suggested.
“Bowel cancer in people under 50 is increasing everywhere, including in Britain, and it’s becoming more and more of a problem,” said Dr Kevin Monahan, consultant gastroenterologist at St Mark’s Hospital.
In the UK, rates have increased by 51% in those aged 25-49 since the early 1990s although the majority of cases still occur in older adults.
Monahan said the archives contain samples from every bowel cancer patient treated at the hospital, making it a unique resource probably anywhere in the world for uncovering causes in young people.
The bowel cancers and accompanying gut bacteria have been preserved in paraffin wax, and are now being sent to the Institute of Cancer Research (ICR) for detailed molecular analysis that has only recently become possible.
Different causes of cancer leave different marks or signatures in the DNA of the cells that have become cancerous. Tracking how common different signatures are over time could point to the likely cause of cancer in young people.
Professor Trevor Graham, from the ICR, said: “Our leading idea is that there’s a particular kind of E. coli that lives in the bowels of young people today that wasn’t there in the past.”
It is thought these bacteria are releasing toxins that damage the DNA inside bowel tissue, turning it cancerous. But this begs the question: why are these bacteria more common now?
“If these so-called bad bugs are causing the increase, we should see that their signature… the damage… was rare in the past and becomes increasingly common as we move towards the present day. We can also test other ideas too,” he added.
But whatever is behind the increase, the archives are “a real treasure trove”, he said. “I think the answer might be in this room.”
See more from MedicalBrief archives:
Why colorectal cancers are rising in young people – US nurses’ study
US studies show colorectal cancer link to ultra-processed foods
Why are so many millennials getting cancer?
Gut E coli may have role in under-50s bowel cancer – global study