Effects of exercise on inflammation, circulating tumor cells, and circulating tumor DNA in colorectal cancer.
Level 2 - randomized trial
Individual randomized controlled trial
PubMed 40107449 · doi:10.1016/j.jshs.2025.101036
What was done
Sixty stage I–III colorectal cancer survivors (mean age 60.6 ± 10.8 years, 65% female, 77% colonic primary) were randomized to 12 weeks of home-based moderate-intensity aerobic exercise or a waitlist control group. Co-primary endpoints were high-sensitivity C-reactive protein (hs-CRP) and interleukin-6 (IL-6). Secondary endpoints were soluble tumor necrosis factor-α receptor 2 (sTNFαR2) and circulating tumor cells (CTCs). The exploratory endpoint was tumor fraction quantified from circulating tumor DNA (ctDNA). Fifty-nine participants completed the study.
What was found
Exercise adherence was 92% (95% CI: 86–99%). Exercise improved submaximal fitness capacity by 0.36 metabolic equivalents (95% CI: 0.05–0.67; p = 0.025) and moderate-to-vigorous physical activity by 34.8% (95% CI: 11.3–63.1; p = 0.002) compared to control. Exercise did not significantly alter primary inflammatory or liquid biopsy endpoints compared to control: - hs-CRP: +20.9% (95% CI: -17.1 to 76.2; p = 0.32), though in a subgroup with elevated baseline hs-CRP (n = 35), exercise reduced hs-CRP by -35.5% (95% CI: -55.3 to -3.8; p = 0.031). - IL-6: +11.4% (95% CI: -7.5 to 34.0; p = 0.25). - sTNFαR2: -3.6% (95% CI: -13.7 to 7.7; p = 0.52). - CTCs: +0.59 cells/mL (95% CI: -0.33 to 1.51; p = 0.21), with higher adherence correlating with reduced CTCs (ρ = -0.37, 95% CI: -0.66 to -0.08; p = 0.013). - ctDNA tumor fraction: 0.0005 (95% CI: -0.0024 to 0.0034; p = 0.73).
Why it matters
A 12-week home-based aerobic exercise program improves cardiorespiratory fitness in colorectal cancer survivors but does not appear to change systemic inflammation or circulating tumor markers in the overall group.
Limits
The study had a small sample size (n = 60) and a short 12-week intervention duration. Subgroup reductions in hs-CRP and correlations between exercise adherence and CTCs were secondary/exploratory. Clinical cancer recurrence and survival were not evaluated.
Cited by
- contradicts Engaging in physical activity reduces the risk of cancer recurrence and metastasis in individuals with circulating tumor cells.