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A randomized international trial found that a structured exercise program after chemotherapy improved outcomes for people with treatable colon cancer, with researchers reporting fewer cancer events and fewer deaths over long-term follow-up.
The study was designed to address a key limitation of prior research: earlier evidence had largely come from comparing more active patients with more sedentary ones, which cannot prove cause and effect. In the new trial, researchers randomly assigned participants to receive either a program designed to promote fitness and nutrition or a coaching-based exercise intervention.
The coaching intervention drew on regular contact, with meetings every two weeks for a year and then monthly for the next two years. Coaches helped participants identify ways to increase physical activity, and many participants chose walking; the Associated Press reported that one participant, Terri Swain-Collins of Kingston, Ontario, walked for about 45 minutes several times a week.
In interviews, Swain-Collins said the routine helped her maintain motivation and accountability. She described how regular check-ins made it harder to fall short, saying she “wouldn’t want to go there and say, ‘I didn’t do anything,’ so I was always doing stuff and making sure I got it done.”
Independent medical experts called the study notable for its evidence quality. Dr. Jeffrey Meyerhardt of Dana-Farber Cancer Institute, who was not involved in the research, said: “It’s an extremely exciting study.” He added that it “is the first randomized controlled trial to show a reduction in cancer recurrences and improved survival linked to exercise.”
Dr. Julie Gralow, chief medical officer of the American Society of Clinical Oncology, also praised the trial, saying, “This is about as high a quality of evidence as you can get,” and saying she “love[s] this study because it’s something I’ve been promoting but with less strong evidence for a long time.”
Researchers followed 889 patients who had completed chemotherapy. The trial was carried out across Canada, Australia, the United Kingdom, Israel and the United States, and the findings were featured at the American Society of Clinical Oncology’s annual meeting in Chicago before being published in the New England Journal of Medicine.
Over eight years, the group assigned to structured exercise became more active than the control group and had better clinical outcomes. The Associated Press reported that the exercise group had 28% fewer cancers and 37% fewer deaths from any cause, while researchers also documented more muscle strains and other similar problems in the exercise group. The study co-author Dr. Christopher Booth of Kingston Health Sciences Centre said the team was “just astounded” when they saw the results.
Booth also characterized the intervention as relatively affordable compared with some medical therapies, saying exercise coaching could cost “several thousand dollars per patient” and calling it “a remarkably affordable intervention that will make people feel better, have fewer cancer recurrences and help them live longer.”
The researchers also collected blood from participants, and they said they will look for clues that could help explain how exercise might affect cancer recurrence and survival. The Associated Press said follow-up work would examine mechanisms such as insulin processing and immune-system changes.
Swain-Collins’ coaching program ended after the trial period, but she continued exercising and said she listens to music while walking in the countryside near her home. Co-author Kerry Courneya, who studies exercise and cancer at the University of Alberta, said behavior change can come when people believe exercise will help, find ways to make it enjoyable, and have a social component. Courneya told the Associated Press, “Now we can say definitively exercise causes improvements in survival.”