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Bowel cancer rates are rising in young people, and researchers are working tirelessly to find out why, writes Dr Lisa Mielke.
As a researcher specialising in bowel cancer, the information shared in the Four Corners “Generation Cancer” episode on ABC was no news to me. Those working in my field have been aware of the sharp rise in bowel cancer in younger people for a long time. But the bravery displayed by Chris Burton, just 39 years old and diagnosed with bowel cancer shortly after his honeymoon, is what inspires cancer researchers in our work.
I am certain this important piece of TV sparked interest among many in the health care community. I therefore wanted to take this opportunity to share some of the existing research findings in this space, and possible avenues being investigated to slow down this increase in bowel cancer in young people.
The Lancet published a groundbreaking study earlier this year, highlighting that cases of bowel cancer in young people of western high-income countries were increasing, with Australia coming first in this undesirable leaderboard.
As the world learns about this unexpected killer, cancer researchers are working tirelessly to find answers to this new problem.
For a long time, we have known that diet can influence the likelihood of developing bowel cancer, such as excessive alcohol consumption and eating large amounts of red and processed meats. But there are newer and more unexpected findings that are helping us piece together this complex puzzle.
The potential risk factors linked to bowel cancer in younger people
One of my key areas of interest as a cancer researcher is the human microbiome and the mechanisms that link the microbiome to overall immune cell health. This includes understanding what role cancer-causing bacteria play and how they influence protective immunity in the gastrointestinal tract.
There are still many aspects of our microbiome that we do not understand, which could provide the key to understanding the rise of bowel cancer in young people.
A recent study published in Nature found that people exposed to the colibactin toxin produced by Escherichia coli were more likely to develop bowel cancer at a younger age. The colibactin toxin is shown to induce mutations in the DNA of the APC (Adenomatous polyposis coli) driver gene, which produces a crucial tumour suppressor protein.
An emerging area of focus has been on the harm caused by microplastics, which humans are now exposed to every day through what we eat, drink and touch. This avenue provides some compelling clues as to why the shift in bowel cancer incidence occurred around 50 years ago, when plastic became such a significant part of modern life.
An area that I am particularly interested in is the increased use of antibiotics and their effect on our microbiome. The microbiome is rich in bacteria that have a protective effect against bowel cancer. However, antibiotics can kill those good bacteria and leave the bad bacteria to release toxins and other substances that damage our DNA over time.
Finally, lifestyle changes linked to stress and circadian rhythm have also been associated with the development of bowel cancer in preclinical models. With our lives becoming busier due to advancements in technology and higher productivity expectations, humans are experiencing stress like never before.
What can protect us?
As we are still learning about the risk factors, it is important to remain focused on what can protect us and our gut health.
Recent studies have shown that a diet containing dairy can help protect against bowel cancer development. The reasons are not fully understood, but it could be due to the high concentration of calcium, vitamin D or lipids.
Aspirin has been shown to have a protective effect against bowel cancer. With prescriptions of aspirin dropping since the 1950s, which correlates with the increase in bowel cancer in younger people, this could become an interesting research avenue.
Today, there are global efforts to help us answer these big questions. The Global Early Onset CRC Think Tank, which I was invited to attend in June 2025, brought together international experts to develop new strategies to slow down the alarming increase in bowel cancer cases. It was a productive discussion that kickstarted cross-continental collaboration between passionate researchers in the bowel cancer space, and I look forward to the insights that will be shared among this network.
Hope for the future
Despite the stark increase in bowel cancer in younger Australians, the number living with the disease is still low, with 1700 under the age of 50 years diagnosed each year. It is important to educate our community about the possibility of developing a cancer that has been labelled an “older person’s cancer”, but not to spread fear.
My message to health care professionals who are working tirelessly to keep our community healthy is to continue to raise awareness of the symptoms among their younger patients. Some symptoms, such as significant fatigue, are linked to bowel cancer. Patients should be reminded to “trust their gut”.
Finally, lowering the age of access to screening from 45 years will be made possible with technological improvements to make it more affordable. My hope is that, one day, the bowel cancer screening program could follow a similar trajectory to the current cervical screening program, which aims to eradicate cervical cancer by 2035.
Dr Lisa Mielke is Head of the Mucosal Immunity and Cancer laboratory at the Olivia Newton-John Cancer Research Institute, and a Cancer Program Lead for the La Trobe Institute of Molecular Sciences, La Trobe University. Dr Mielke is an expert in immune cell biology, intestinal homeostasis and colorectal cancer.
The statements or opinions expressed in this article reflect the views of the authors and do not necessarily represent the official policy of the AMA, the MJA or InSight+ unless so stated.
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