Colonoscopies and the functioning of our gastrointestinal tract are not typical topics for discussion on a blog site dedicated to looking at the future. That is, unless you are over age 40 these days.
That’s because in my part of the world, Canada, routine screening for intestinal problems is increasingly common. Why? Because diseases of the digestive tract are on the rise, including increasing colorectal cancer, irritable bowel syndrome (IBS), and inflammatory bowel diseases like Crohn’s, colitis and ulcerative colitis.
It is not just a Canadian or American problem, but one that is increasingly prevalent around the world as the population ages, and as more Global South countries adopt Western (red meat) diets.
Why am I writing about this today? In the last month, I needed a bowel screening test called a flexible sigmoidoscopy. I was experiencing bleeding coming from my lower bowel. I knew it was from the lower bowel because the blood was red. If the bleed was happening in my upper gastrointestinal tract from the esophagus to the stomach and small intestine, the blood would have been much darker. In my case, the bleeding turned out to be coming from hemorrhoids and could be quickly remedied.
The flexible sigmoidoscopy is the junior cousin of a colonoscopy. I am due for the latter in two and a half years because, after age 50, when colonoscopy screening every 8 to 10 years was recommended by my family doctor, I had one, which found an adenoma, an intestinal polyp that was removed by the gastroenterologist during the test. Adenomas are non-cancerous tumours. They can become cancerous over time, usually between 5 and 15 years. That’s why periodic screening is important.
The normal screening for bowel abnormalities is done using a fecal immunochemical test (FIT). A FIT should be done every two years for people with a family history of colorectal cancer. It comes in a kit that includes everything you need to collect a stool sample, which is sent to laboratories for testing.
So, when do you need a colonoscopy? If there is a family history of colorectal cancer, or if there is unexplained weight loss or intestinal bleeding, a colonoscopy is advisable. A positive FIT test should lead to a follow-up colonoscopy. Otherwise, a colonoscopy can be used to screen for adenomas and colorectal cancer starting at age 50. The increasing appearance of colorectal cancer in people in their forties may change these screening recommendations in the future.
Using a colonoscopy for people with a family history of colorectal cancer, bleeding polyps, and IBS has found at least one adenoma between 25% and 34% of the time. A large adenoma (2 centimetres or bigger) represents a higher cancer risk between 20% and 30%. Smaller ones between 1 and 2 centimetres have a 10% cancer risk, while ones smaller than a centimetre are less than a 1% risk.
That’s why the colonoscopy has been the gold standard for intestinal cancer screening, that is, until now. Researchers at the University of Geneva in Switzerland may make the colonoscopy a thing of the past. They are using artificial intelligence (AI) to diagnose colorectal cancer through the analysis of gut microbes. In a paper published in August 2025 in the journal Cell Host & Microbe, a comprehensive study of human gut microbiota across different and distinct populations worldwide was conducted using a large dataset from colorectal cancer patients. The researchers developed a machine learning (ML) algorithm and a comprehensive catalogue of human gut microbiota subspecies to develop a sampling tool with predictive power approaching that of colonoscopies.
According to Professor Mirko Trajkovski, from the Department of Cell Physiology and Metabolism at the University, “Our method detected 90% of cancer cases, a result very close to the 94% detection rate achieved by colonoscopies and better than all current non-invasive detection methods.”
Mirko stated that training the algorithm with even larger datasets should make this method as accurate as a colonoscopy, serving as an alternative and simpler replacement for colorectal cancer screening. A clinical trial is soon to begin with the Geneva University Hospitals.
Does this mean colonoscopies will become a thing of the past? Possibly, and for those of us who have to go through the two-day prep required each time we have the test, we won’t be complaining.
An additional benefit is that the ability of the AI to differentiate subspecies of microbiota should make it possible to develop non-invasive diagnostic tools to ferret out many other diseases through analysis of bacterial samples.
