Physical activity

Among approximately 170,000 women in the Norwegian Women and Cancer Study, a higher HLI score — incorporating physical activity, BMI, smoking, alcohol, and diet — was associated with significantly lower colorectal cancer risk. For women diagnosed with colorectal cancer, a higher prediagnostic HLI score showed weak negative associations with mortality. Cox proportional hazard models were used to estimate these associations across the prospective cohort.

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In the NOWAC cohort of 35,525 Norwegian women, the population attributable fraction of colon cancer due to low physical activity was 10.8% (95% CI −0.7% to 21.0%). Although the confidence interval narrowly crosses zero, the point estimate indicates physical inactivity contributes meaningfully to colon cancer burden. This was one of seven modifiable factors assessed using a parametric piecewise constant hazards model accounting for competing risk of death, which jointly explained 46.0% (95% CI 23.0%-62.4%) of incident colon cancer cases.

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Across multiple epidemiological studies assessed in this systematic review, physical activity and cardiorespiratory fitness showed an inverse association with colon cancer and all-cancer sites combined in both sexes. The protective effect of physical activity on colon cancer risk operated independently of body mass index status. However, formal evaluation of the interaction between body mass and physical activity levels found no evidence that high fitness eliminates obesity-conferred cancer risk. Both healthy weight and recommended physical activity levels are needed concurrently to maximally impact colorectal cancer risk reduction.

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In the BeWEL randomized controlled trial (n=163 intervention participants), a combined diet and physical activity programme produced significantly greater weight loss than controls at 12 months in overweight adults with colorectal adenoma. Physical activity was a key intervention component alongside dietary modification. At baseline, more deprived participants (n=58) spent significantly less on physical activity than less deprived participants (n=105, p=0.003), yet both groups achieved comparable improvements in body weight and secondary outcomes including cardiovascular risk factors and physical activity levels at 12 months, with no significant between-group differences detected by deprivation status.

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In this RCT involving 78 participants with a family history of colorectal or breast cancer, the 12-week lifestyle intervention produced favourable increases in physical activity measured by accelerometer. Baseline accelerometer data were attained by 84% of participants and 54% at follow-up. The intervention arm received a personalized physical activity programme using behavioral change techniques including motivational interviewing, action plans, coping plans, and implementation intentions.

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Among 181 non-metastatic colorectal cancer patients undergoing curative surgery, 8.5% had physical difficulty climbing stairs at pre-operative assessment. Physical capacity independently affected survival (P<0.05), with patients who had difficulty climbing stairs showing a hazard ratio of 3.31 for poorer survival compared to those without difficulty. This effect was independent of age, BMI, and histopathological stage across 480 person-years of follow-up.

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Non-randomized interventional study of 39 locally advanced rectal cancer patients (27 males). All participants showed significant post-chemoradiotherapy reductions in daily step count (median 4966 to 3044, p<0.0001), active energy expenditure (264 vs 154 kcal, p=0.003), and MET (1.3 vs 1.2, p=0.010). Twenty-three participants completing a 6-week exercise programme demonstrated significantly improved sleep efficiency versus 10 usual care controls (exercise: 80% to 78%; control: 69% to 76%; between-group p=0.022). Sleep duration and lying down time also improved significantly in the exercise group (p<0.05). Active energy expenditure (exercise: 152 to 434 kcal vs control: 244 to 392 kcal) and MET (exercise: 1.3 to 1.5 vs control: 1.1 to 1.5) favored the exercise group but did not reach statistical significance (p>0.05). All 23 exercise participants completed the programme (100% adherence).

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A systematic review searched WEB OF SCIENCE, SCOPUS, and SPORTDISCUS databases through February 2016, retaining 23 full-text articles examining factors associated with physical activity participation in colorectal cancer patients. Four major categories of factors were identified: sociodemographic factors, health factors (disease-specific and non-specific), prior experience and preferences, and motivational factors. Despite evidence of physical and psychosocial benefits, the review found that most colorectal cancer patients do not meet recommended physical activity criteria. Key facilitators across the 23 studies included positive attitude, family support, basic psychological need satisfaction, and self-determined motivation. Barriers included comorbidity and receipt of adjuvant therapy with associated side effects such as fatigue and nausea. The review concluded that adapted physical activity programs incorporating motivational strategies are needed for this population.

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In this randomized controlled trial of 329 participants diagnosed with colorectal adenoma through the Scottish Bowel Screening Programme, the intervention group receiving diet and physical activity education with behavioral change techniques showed significantly better physical activity measures than the control group at 12-month follow-up. At baseline, awareness of lifestyle risk factors was low, with a mean knowledge score of only 1.5 out of 6 (SD 1.1, range 0–5). Forty participants (12%) reported no knowledge of any CRC risk factors, and 36 (11%) could not identify specific diet or activity factors. An estimated 47% of colorectal cancers could be prevented through appropriate lifestyle behaviors including physical activity.

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This systematic review of gene-meat interactions in CRC, based on searches of PubMed and Embase with 239 initial records, references the World Cancer Research Fund 2014 comprehensive evaluation identifying physical activity as a factor that protects against colorectal cancer. The WCRF estimated that half of all CRC cases may be prevented through relevant lifestyle changes including increased physical activity. The review's own analysis demonstrated that inflammatory pathways are central to meat-related carcinogenesis, with significant gene-meat interactions in PTGS2 encoding COX-2 (Pint = 0.006) and NFKB1 (Pint = 0.03). Physical activity's known anti-inflammatory effects may modulate these same pathways, reducing colorectal cancer risk alongside dietary modifications.

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A year-long randomized controlled trial of 641 older, overweight, long-term breast, prostate, and colorectal cancer survivors tested a telephone and mailed print diet-exercise intervention. Session attendance had significant positive indirect effects through exercise behavior on physical function (β = 0.11, p < 0.05), basic lower extremity function (β = 0.10, p < 0.05), advanced lower extremity function (β = 0.09, p < 0.05), and mental health (β = 0.05, p < 0.05), along with a negative indirect effect on BMI (β = -0.06, p < 0.05). Dietary and exercise behaviors were tracked at 14 time points.

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In this cohort of 1,011 stage III colon cancer patients, the combination of low physical activity (<18 MET-hours/week) and overweight status (BMI ≥25 kg/m²) amplified the negative impact of sugar-sweetened beverage consumption on outcomes. Among this subgroup, high sugary drink intake was associated with HR = 2.22 (95% CI, 1.29–3.81, Ptrend = 0.0025) for recurrence or death. The study built on prior findings linking sedentary lifestyle with increased recurrence risk in colon cancer patients.

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Meta-analysis of 20 studies using random effects models demonstrated a significant inverse association between physical activity and colon adenoma risk, with an overall relative risk of 0.84 (95% CI: 0.77–0.92). The protective effect was consistent across sexes: men RR=0.81 (95% CI: 0.67–0.98) and women RR=0.87 (95% CI: 0.74–1.02). A notably stronger association was observed for large or advanced polyps with RR=0.70 (95% CI: 0.56–0.88), representing a 30% risk reduction for the most clinically significant precancerous lesions. The systematic review covered studies published through April 2010.

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Using WHO global burden of disease data, a UK health economic evaluation identified colon and rectum cancer as one of five diseases with mortality and morbidity directly attributable to physical inactivity. Population attributable fractions were applied to UK Health Service cost data, yielding a total direct NHS cost of £1.06 billion across all five attributable diseases. Physical inactivity accounted for 3% of all disability adjusted life years lost in the UK in 2002. Only 33% of men and 25% of women met government physical activity targets.

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Hospital-based case-control study in Hong Kong with 822 cases and 926 controls. Those in the highest tertile of weekly moderate-to-active physical activity (>38.5 hours) had significantly lower colorectal cancer risk (adjusted OR=0.75; 95% CI, 0.58-0.97). Weekly activity intensity measured in MET-hours showed dose-response reductions for colon cancer (P for trend=0.005) and rectal cancer (P for trend=0.023), with highest tertile adjusted OR of 0.63 for colon and 0.68 for rectal cancer. Leisure-time exercise at least 28 times per month reduced colorectal cancer risk (adjusted OR=0.59; 95% CI, 0.39-0.89). Combined activity assessment showed achieving 2, 3, and 4 target activity levels reduced risk by 35%, 50%, and >90% respectively (P for trend=0.000 for colon, 0.001 for rectal cancer).

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