Canfit EP
2 June 2026
June is Bowel Cancer Awareness Month in Australia, and this year there is genuinely exciting news for anyone living with, or recovering from, bowel cancer. A landmark clinical trial — the biggest of its kind ever conducted — has confirmed what exercise physiologists have long suspected: structured exercise after bowel cancer treatment can significantly reduce the risk of cancer coming back, and help people live longer.
Bowel cancer (also called colorectal cancer, or CRC) is Australia's second most common cancer, affecting both men and women. Around 15,000 Australians are diagnosed each year, and approximately 30% of people diagnosed with stage III colon cancer will experience a recurrence after treatment.
The CHALLENGE Trial: A World First
The CO21 CHALLENGE Trial took place over 17 years and followed 889 colon cancer patients across six countries, including Australia, Canada and the UK. Participants had all been previously treated using surgery and chemotherapy, and were randomly assigned either to a three-year structured exercise programme, or to a health education programme.
After a median follow-up of 7.9 years, 93 patients in the structured exercise programme had their cancer recur, compared to 131 patients in the health education group. At five years, the disease-free survival rate was 80% in the structured exercise programme and 74% in the health education group. Patients in the structured exercise programme had a 28% lower risk of recurrent or new cancers developing.
After 8 years, overall survival was 90% in the structured exercise programme and 83% in the health education group — meaning patients had a 37% lower risk of death if they participated in the structured exercise programme.
The results were published in the prestigious New England Journal of Medicine and presented at the 2025 American Society of Clinical Oncology (ASCO) Annual Meeting — the world's largest oncology conference.
"Our findings show that exercise is no longer just a quality-of-life intervention for cancer patients that can be offered when and where possible. It is a treatment for colon cancer that must be made available to all patients." Canadian Cancer Society — Dr Kerry Courneya, study co-chair.
Notably, the Australian arm of this international trial was co-led by Professor Janette Vardy from the University of Sydney, funded by the National Health and Medical Research Council — making this a landmark result for Australian cancer research too.
What Did the Exercise Programme Look Like?
The structured exercise programme tested in the trial lasted three years and involved people regularly meeting with an expert physical activity consultant. For the first six months, participants received in-person coaching sessions every week. Over time, this was reduced to one session per month, either in person or online. The goal was to increase exercise levels by at least the equivalent of a 30-minute jog every other day.
Participants chose their own forms of moderate-intensity exercise — from walking to pickleball — with personalised support being key to their success.
How Does Exercise Fight Bowel Cancer? The Science Behind It
The mechanisms are multi-layered. Recent research published in Gastroenterology (2025) highlights the role of myokines — signalling molecules released by contracting muscles during exercise. Cross-talk between active skeletal muscles and the gut microbiota reveals how regular physical activity boosts host immunity, facilitates a more diverse gut microbiome and functional metabolome, and plays a positive role in energy homeostasis and metabolic regulation.
A healthy gut microbiome is closely linked to bowel cancer risk. Exercise restores bacterial balance by boosting the relative number of butyrate-producing bacteria and the ratio of Bacteroidetes to Firmicutes, which can enhance the intestinal level of butyrate and short-chain fatty acids (SCFAs) — and lower the risk of colorectal cancer.
In simple terms: exercise helps keep the gut environment hostile to tumour development.
See the GLOSSARY below for key terms in bold.
Recommended Activity Levels (Bowel Cancer Survivors)
Based on the CHALLENGE trial and current guidelines:
Aerobic exercise: Work towards at least 150 minutes of moderate-intensity activity per week (e.g. brisk walking, cycling, swimming)
Strength training: At least 2 sessions per week
Start low, build gradually: Especially during or shortly after chemotherapy
Seek support: Working with an Accredited Exercise Physiologist ensures your programme is safe, progressive, and tailored to your stage of recovery
GLOSSARY
Myokines: Signalling proteins released by muscles during exercise that communicate with other organs — including the gut and immune system — to produce protective effects throughout the body.
Gut Microbiome: The vast community of trillions of microorganisms (bacteria, fungi, viruses) living in the digestive tract. A diverse, balanced microbiome is associated with lower cancer risk and better treatment outcomes.
Butyrate: A short-chain fatty acid produced when beneficial gut bacteria break down dietary fibre. It plays a key role in maintaining a healthy colon lining and has anti-tumour properties.
Short-Chain Fatty Acids (SCFAs): Metabolites produced by beneficial gut bacteria that help regulate inflammation, support immune function, and protect the gut wall.
Dysbiosis: An imbalance in the gut microbiome — a reduction in beneficial bacteria and an overgrowth of harmful ones — which has been linked to increased inflammation and colorectal cancer risk.
Disease-Free Survival: A clinical measure of how long a patient lives without their cancer returning after treatment. A key outcome measured in cancer trials.
MET-hours: A unit used to measure the total amount of physical activity. One MET (Metabolic Equivalent of Task) represents energy used at rest; higher MET values mean more intense activity.
SOURCE LIST
Source: Courneya KS, Vardy JL, O'Callaghan CJ et al. Structured exercise after adjuvant chemotherapy for colon cancer. N. Engl. J. Med. doi:10.1056/NEJMoa2502760 (2025)
Source: Hawley JA et al. Exercise, the Gut Microbiome and Gastrointestinal Diseases: Therapeutic Impact and Molecular Mechanisms. Gastroenterology. Vol 169, Issue 1, pp48 –62 (2025)
https://www.gastrojournal.org/article/S0016-5085(25)00329-4/fulltext
