Landmark Clinical Trial Shows Exercise Improves Colon Cancer Survival 

In a world-first clinical trial, researchers working with the Canadian Cancer Trials Group (CCTG) have demonstrated that a structured exercise program significantly improves survival for colon cancer patients by reducing the risk of disease recurrence and new primary cancers.

The CO21 CHALLENGE trial results were presented today at the American Society of Clinical Oncology (ASCO) 2025 annual meeting and simultaneously published in the New England Journal of Medicine. The groundbreaking seventeen-year study is the first of its kind to conclusively answer a long-standing question in oncology: Can physical activity improve cancer survival? 

“As oncologists, one of the most common questions we are asked by patients is what else they can do to improve their outcomes,” said study co-chair, Dr Christopher Booth, Medical Oncologist at Kingston Health Sciences Centre and Professor of Oncology at Queen’s University. “The CO21 trial provides an answer: an exercise program after surgery and chemotherapy, reduces the risk of recurrent or new cancer and improves survival, allowing patients to live longer and better lives.”

The trial results revealed a significant improvement in overall survival and disease-free survival among participants assigned to the exercise program, compared to those who only received health education materials. Patients in the structured exercise program had a 37% lower risk of death and a 28% lower risk of recurrence or developing other cancers. 

“Our study shows that exercise is no longer just a quality-of-life intervention—it is a treatment for colon cancer that must be made available to all patients,” said Dr Kerry Courneya, Professor and Canada Research Chair in Physical Activity and Cancer, University of Alberta and the CO21 study co-chair.

The study integrated physical activity into post-treatment care with the guidance of a physiotherapist or kinesiologist. Each participant chose their own forms of moderate-intensity exercise with the goal of adding 2.5 hours of exercise per week. 

“That sense of accountability made all the difference. Simply being told to exercise by a physician wouldn’t have been enough; having someone walk alongside me, guide me and check in regularly was what truly made it possible,” says Terri Swain-Collins, (pictured above with physiotherapist Alison MacDonald) a participant in the trial. Working with a trainer over the 3-year study period allowed her to establish and maintain a fitness routine personalized to her needs.

Researchers believe these findings should affect clinical guidelines globally, positioning exercise alongside chemotherapy and surgery as standard components of care for colon cancer. The bottom line is that if we want better outcomes, patients need support to change their lifestyles, with personal trainers embedded in the cancer system as part of the treatment team. 

“The Canadian Cancer Trials Group is delighted to have once again led an international cancer clinical trial that will change practice globally and improve outcomes for patients,” said the study’s Senior Investigator, Dr Chris O’Callaghan. “With these results, the CHALLENGE trial will mark a turning point in the treatment of colon cancer.” 

“By bridging the gap between bold ideas and routine practice, clinical trials are essential to driving research progress that can benefit patients,” says Dr Stuart Edmonds, Executive Vice President, Mission, Research and Advocacy at the Canadian Cancer Society. “The results of this trial have the potential to save and improve lives for the tens of thousands of people in Canada affected by colorectal cancer each year, and we are proud our donors enabled us to support it.” 

About the trial

CCTG CO21 CHALLENGE was a phase III randomized trial of the impact of a physical activity program on disease-free survival in patients with stage III or high-risk stage II colon cancer.

Between 2009 and 2024, the international trial enrolled 889 patients who had completed surgery and adjuvant chemotherapy for stage III or high-risk stage II colon cancer. The patients were randomly assigned to participate in a 3-year structured exercise program (445 patients) or to receive health education materials promoting physical activity and healthy nutrition (444 patients). All patients also received standard cancer surveillance and follow-up care. 

Patients in the exercise program met with the exercise specialist once every two weeks to monitor progress for the first year and then monthly for two more years. The goal was to help them add 2.5 hours of aerobic exercise per week to their usual activity levels and sustain this amount of physical activity for 3 years.

At five years, the disease-free survival rate was 80% in the structured exercise program and 74% in the health education materials group. Patients in the structured exercise program had a 28% lower risk of recurrent or new cancer than patients who only received health education materials. 

After eight years, overall survival was 90% in the structured exercise program and 83% in the health education materials group. Patients in the structured exercise program had a 37% lower risk of death than patients who only received health education materials. 

The international study co-chair was Dr Janette Vardy, from The University of Sydney (Australia) with funding from National Health and Medical Research Council. The UK team was led by Dr Victoria Coyle at Queen’s University of Belfast, supported by Cancer Research UK. This trial was made possible through the support of the Canadian Cancer Society.