Physical activity has been linked to cancer outcomes in observational studies, but sustaining moderate-to-vigorous activity over the long term remains a challenge for survivors of colon cancer. A new phase 3 analysis from the CHALLENGE trial — the first randomised clinical trial of exercise designed to test effects relevant to cancer-related survival — reports that a structured exercise program significantly strengthened key motivational and behavioural beliefs that underpin long-term adherence to physical activity among patients who had completed curative treatment for colon cancer.
The CHALLENGE trial enrolled patients with resected colon cancer who had completed chemotherapy and randomised them to one of two groups: a structured exercise program (SEP) involving 48 behavioural support sessions delivered over three years, designed to increase and sustain moderate-to-vigorous physical activity (MVPA), or a control group receiving standardised health education materials (HEM). The intervention was grounded in social cognitive theory and aimed not just to prescribe exercise but to modify beliefs about benefits, opportunities, confidence, and planning that drive behaviour change.
CLINICAL SUMMARY
What was examined
Patients who completed chemotherapy for resected colon cancer were randomised to a structured exercise program with behavioural support or to standard health education materials; social cognitive beliefs about exercise were assessed over three years.
Key findings
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The structured exercise program was associated with greater improvements in perceived benefits, enjoyment, confidence, motivation, support, opportunity, and planning related to physical activity compared with health education alone (all P < .01).
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These motivational constructs were significantly associated with self-reported moderate-to-vigorous physical activity at all follow-up points.
Clinical implications
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Behavioural support delivered through a structured exercise program may enhance key social cognitive drivers needed for long-term physical activity adherence in colon cancer survivors.
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Strengthening motivation, confidence, and planning could be integral to designing effective exercise interventions that ultimately influence cancer-related survival outcomes once fully reported.
To understand how the SEP influenced patients’ motivational profiles, researchers assessed social cognitive constructs — including perceived benefits of physical activity, enjoyment, confidence, social support, motivation, opportunity, and planning — using single-item questions on 5-point scales at baseline and then every six months during the three-year intervention period. Regression models for repeated measures estimated changes in these social cognitive variables over time between the SEP and HEM groups.
Across 889 randomised survivors (445 in SEP, 444 in HEM) enrolled between 2009 and 2024, the structured exercise intervention was associated with significantly more favourable social cognitive beliefs about exercise at nearly all measured time points. The analysis reported average intervention effects (AIE) favouring SEP for multiple constructs: perceived benefit (AIE = 0.29; P < .001), enjoyment (AIE = 0.40; P < .001), difficulty (AIE = –0.18; P = .003), confidence (AIE = 0.28; P < .001), support (AIE = 0.59; P < .001), motivation (AIE = 0.47; P < .001), opportunity (AIE = 0.31; P < .001), and planning (AIE = 0.82; P < .001). All social cognitive measures were significantly associated with self-reported MVPA at all time points, suggesting that SEP not only influenced beliefs but that these beliefs were linked to actual physical activity behaviour.
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The findings underscore that achieving long-term increases in physical activity after cancer treatment may require more than just advice or education: it may depend on structured behavioural support that meaningfully shifts patients’ beliefs about physical activity. SEP participation was tied to stronger perceptions of the benefits of exercise, greater enjoyment, higher confidence and motivation, and improved planning — all of which are foundational components of sustained behaviour change according to social cognitive theory.
Although the main clinical outcomes of the CHALLENGE trial — including effects on disease-free survival and other hard endpoints — will take years to fully mature, this analysis provides early evidence that a robust behavioural intervention can modify psychological drivers that have been linked to sustained activity and, in observational studies, to better survival and lower recurrence in colon cancer survivors.
Because lifestyle interventions are increasingly recognised as a component of survivorship care, these results have relevance for clinicians, rehabilitation specialists, and survivorship programme designers who aim to integrate exercise into care pathways. The long-term impact of such changes in social cognitive beliefs on objectively measured activity and cancer outcomes remains a priority for ongoing analysis as the CHALLENGE trial continues.
Paper: Courneya, K.S., et al. Effects of a structured exercise program on motivational outcomes in patients with Colon cancer, JNCI: Journal of the National Cancer Institute, 2026; djag023, Access online here.
Editor’s Recommended Resource: Supportive Care Matters Podcast: Series 2 | Episode3: Getting Exercise to Improve Cancer Survival? Challenge Accepted! Listen here or wherever you get your podcasts.
