Bowel cancer is the third most common type of cancer in Australia and treating it is both costly and complex. Alarmingly, rates are rising among people under 50, and researchers still don’t know why.
It is for these reasons that Professor Mark Molloy is on a mission to prevent the disease in the first place. Based in the Kolling Institute, the leading bowel cancer research specialist is running several projects looking at early detection.
He says the first promising pathway is a blood test.
Currently, the main screening method is a government-funded test that detects blood in the stool. It’s mailed to people over 50, but Professor Molloy says because it requires them to collect the sample themselves, only around 40 per cent return a completed test.
“They don’t like handling a stool sample, and early cancers may not leak blood they can go undetected by this method," he said.
"We’re very interested in whether we can move to a blood test — and not just any blood test. We’re working to do this from a few drops of blood collected from a finger prick.”
Working with scientists from Sangui Bio, a biotechnology partner of the Kolling Institute, Professor Molloy has analysed proteins in blood samples from around 1,200 patients. “We can definitely see a signature in the blood from the finger prick sampling that’s linked to the presence of polyps and early cancers, but more research is needed."
Studying polyps
Another focus of the research is improving the follow-up process after a positive screening result. Currently, patients with a positive stool test undergo a colonoscopy, where clinicians look for polyps — small growths in the gut lining that can develop into cancer if not removed.
Gastroenterologists and colorectal surgeons remove the polyps which are then assessed by pathologists, who examine their size and appearance to determine when the patient should return for a follow-up “surveillance” colonoscopy. But current guidelines as to when this should happen is based on limited evidence and can be improved.
“Colonoscopies are a massive resourcing problem for the health system and patients can face delays,” he said.
To address this, Mark and his team are researching a more personalised way to improve the timing of a colonoscopy for higher risk patients with polyps. They recruited patients undergoing a colonoscopy and collected small biopsies from polyps and nearby healthy gut tissue. These samples were then analysed at a molecular level.
“We’ve now identified a number of genes that appear to be linked to higher risk, and this seems to be independent of polyp size” he said.
Following publication of this finding, the team is doing a follow-on study to confirm whether these gene mutations predict future polyp development. If successful, the research could lead to a test that helps prioritise patients for follow-up colonoscopies based on molecular risk — allowing those patients with the highest risks to be seen more quickly than current guidelines dictate.
It is estimated 15,000 Australians are diagnosed with bowel cancer each year. “If you vox popped people in the street, a lot of people would be touched by bowel cancer in some way, if not directly, they would know of someone in their circle."
He said it is unclear why bowel cancer is on the rise, particularly amongst younger people. “Ideas include changing nutrition over time causing changes in our gut microbiome that are known now to be facilitators of some bowel cancers. Then there’s thoughts about the environment – like the abundance of microplastics that we breathe in and consume – or it could be our more sedentary lifestyle.”
He said research is ongoing but there is no agreed upon evidence.
The science is still unfolding, but Professor Molloy’s direction is clear: user-friendly screening, targeted follow-up, and a deeper genetic understanding of what drives this deadly cancer. His various avenues of research will hopefully find more answers and help redefine the future of bowel cancer care.