Associations of adiposity and device-measured physical activity with cancer incidence: UK Biobank prospective cohort study.
Level 3 - non-randomized controlled study
Prospective cohort study
PubMed 39675506 · doi:10.1016/j.jshs.2024.101018
What was done
This prospective cohort study examined 70,747 UK Biobank participants (mean age 61.6 ± 7.9 years, 56.4% women) without chronic diseases or mobility limitations who wore wrist accelerometers. Physical activity was quantified as weekly minutes of light (LPA), moderate-to-vigorous (MVPA), vigorous (VPA), and total volume. Participants were classified into nine joint groups based on physical activity tertiles and body mass index (BMI) categories (normal weight, overweight, and obesity). Cancer incidence and mortality were retrieved from national registries, and associations were calculated as subdistribution hazard ratios over a median follow-up of 6.1 years.
What was found
During follow-up, 2,625 cancer events occurred (2,572 non-fatal and 53 fatal). Compared with the referent group (normal weight and high physical activity), overweight and obesity were associated with a 6% to 36% higher cancer hazard across physical activity intensities. High MVPA (top tertile ~500 min/week) and VPA (top tertile ~32 min/week) attenuated the excess hazard associated with overweight and obesity. Normal-weight status was not associated with increased cancer hazard regardless of physical activity level. Findings were more pronounced for cancer types strongly linked to physical activity.
Why it matters
These findings suggest that while achieving higher volumes of moderate-to-vigorous physical activity helps offset obesity-related cancer risk, maintaining a normal body weight remains comparatively more impactful for risk reduction.
Limits
The study is observational, leaving potential for residual confounding. Physical activity was assessed at a single time point via accelerometer rather than tracked continuously across the lifespan. The median follow-up was relatively short (6.1 years), fatal cancer events were few (n = 53), and confidence intervals for specific hazard estimates were not provided in the abstract.
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