On June 2, 2025, we posted on our Cancer Fitness Blog a summary of the CHALLENGE Clinical Trial: https://cancerfitness.org/blog/structured-exercise-after-adjuvant-chemotherapy-for-colon-cancer-challenge-trial/. The actual results of the Trial had been published online the day before by The New England Journal of Medicine at the same time it was presented at the Annual Meeting of ASCO. The recently published print version of N ENG J MED (7/03/25) carried not only the full manuscript of the CHALLENGE Clinical Trial, but also an accompanying editorial by Dr. Melinda L. Irwin about the results of the trial.
The editorial emphasizes the urgent need to integrate structured physical activity into standard cancer care. Over the past two decades, observational studies have consistently linked postdiagnosis physical activity with improved cancer outcomes, including lower recurrence and mortality rates. Critics have noted these studies’ inability to establish causation but growing biological and clinical evidence — including improvements in immune, metabolic, and inflammatory markers — supports a causal relationship.
The recently completed CHALLENGE trial (Colon Health and Lifelong Exercise Change), a randomized phase 3 study, provides definitive evidence. Involving patients who had completed surgery and adjuvant chemotherapy for stage III or high-risk stage II colon cancer, the trial compared usual health education with a three-year supervised aerobic exercise intervention. After a median follow-up of 7.9 years, those in the exercise group showed a 28% lower risk of recurrence or new cancer and a 37% reduction in overall mortality. At eight years, overall survival was 90.3% in the exercise group versus 83.2% in controls — a significant 7.1 percentage point difference.
Exercise benefits in the trial were consistent across age, sex, and disease subgroups, and were independent of weight loss — despite one-third of participants having a BMI over 30, no significant weight changes occurred. These findings underscore the biological impact of physical activity apart from obesity reduction. However, the trial’s slow enrollment (15 years to recruit 889 patients) highlights the systemic underfunding and logistical barriers for behavioral trials compared to drug studies.
Despite longstanding national guidelines recommending at least 2.5 hours of moderate activity per week, few cancer patients meet these goals. The editorial calls for immediate action: oncology practices should embed trained exercise counselors, refer patients to community or cardiac rehab-style programs, and push for insurance reimbursement. Systems-level change is necessary to overcome current infrastructure and cultural barriers.
Dr. Irwin concludes that with survival benefits comparable to standard therapies and improved quality of life, exercise must become a core component of oncology care. As more large-scale trials in breast and ovarian cancer continue, the evidence base grows stronger. The time for hesitation is over — integrating exercise into cancer treatment is both scientifically justified and morally imperative.
Quoting Dr. Irwin, the last sentence of her editorial states, “As oncology continues to advance, exercise must become a standard part of care. The time to act is now.”
Reference: https://www.nejm.org/doi/full/10.1056/NEJMe2506363
