A new method for detecting bowel cancer is more than 90% accurate at predicting which higher risk people will develop the disease, research found.
People with inflammatory bowel disease (IBD), such as Crohn's and ulcerative colitis, are known to have an increased chance of bowel cancer, but not all will develop it.
Now, a study funded by Cancer Research UK has shown more than 90% accuracy in predicting bowel cancer risk in the next five years in a high-risk group of people with IBD.
This could lead to a blood test which will inform doctors which IBD patients are most at risk of bowel cancer.
IBD can irritate the lining of the bowel and can cause abnormal pre-cancerous cells to form if left untreated.
To identify people's cancer risk, scientists at the Institute of Cancer Research (ICR), working with doctors at St Mark's in London, the UK's specialist bowel hospital, found that people with IBD whose pre-cancerous cells had lost multiple copies of their DNA were far more likely to go on to develop bowel cancer.
The scientists also created an algorithm that calculates the risk of future bowel cancer, based on the exact pattern of the DNA which is altered in the pre-cancerous cells.
Samples of pre-cancerous cells were taken from 122 patients with IBD for the study published in the journal Gut.
About half of the patients went on to develop bowel cancer within five years, while the other half remained cancer-free.
Professor Ailsa Hart, co-lead of the study, from St Mark's, said: "Patients with inflammatory bowel disease have a higher risk of developing colorectal cancer than people without IBD, and need to undergo assessment with regular colonoscopies to try to detect early signs of cancer.
"These tests are onerous and unpleasant for patients, imperfect at detecting early cancer changes and costly to health services.
"If early signs of cancer are detected, surgery, which involves removing the colon, is advocated. Finding smarter ways to assess these colons is much needed.
"Here we describe a potential biomarker, which can be readily translated into clinical practice, to improve assessment of patients with IBD and early signs of cancer to help with the decision for surgery."
Around 500,000 people in the UK are thought to have Crohn's or ulcerative colitis.
Scientists hope their findings could spare people who are at much lower risk from the stress of needing regular colonoscopies or undergoing surgery to remove the colon.
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Professor Trevor Graham, from the ICR, which co-led the research, said: "Most people with ulcerative colitis or Crohn's disease won't develop bowel cancer.
"But for those that have these conditions and are showing signs of pre-cancer in their colon, there are some tough decisions to make.
"Either they have it monitored regularly, in the hope that it doesn't become cancer, or they have their bowel removed to guarantee they don't get cancer in the future. Neither of these options are particularly pleasant.
"Our test and algorithm give people with IBD, and the doctors who care for them, the best possible information so that they can make the right decision about how to manage their cancer risk."
Executive director of research and innovation at Cancer Research UK, Dr Iain Foulkes, said: "Genome sequencing is now far cheaper and more widespread than ever before, and it's changing how we look at cancer.
"Getting a full readout of tumour DNA means we can see a much bigger picture of how someone's cancer started and how it is likely to change over time.
"With this research, we can focus resources on treating people with IBD who are at really high risk, saving health services valuable time and money."
(c) Sky News 2025: New bowel cancer detection method more than 90% accurate, research finds
