Published in BMC Medicine, 18th September 2024
Diurnal timing of physical activity and risk of colorectal cancer in the UK Biobank
Michael J. Stein,
Hansjörg Baurecht,
Patricia Bohmann,
Béatrice Fervers,
Emma Fontvieille,
Heinz Freisling,
Christine M. Friedenreich,
Julian Konzok,
Laia Peruchet-Noray,
Anja M. Sedlmeier,
Michael F. Leitzmann &
Andrea Weber
Abstract
Background
Physical activity reduces colorectal cancer risk, yet the diurnal timing of physical activity in colorectal cancer etiology remains unclear.
Methods
This study used 24-h accelerometry time series from UK Biobank participants aged 42 to 79 years to derive circadian physical activity patterns using functional principal component analysis. Multivariable Cox proportional hazard models were used to examine associations with colorectal cancer risk.
Results
Among 86,252 participants (56% women), 529 colorectal cancer cases occurred during a median 5.3-year follow-up. We identified four physical activity patterns that explained almost 100% of the data variability during the day. A pattern of continuous day-long activity was inversely associated with colorectal cancer risk (hazard ratio (HR) = 0.94, 95% confidence interval (CI) = 0.89–0.99). A second pattern of late-day activity was suggestively inversely related to risk (HR = 0.93, 95% CI = 0.85–1.02). A third pattern of early- plus late-day activity was associated with decreased risk (HR = 0.89, 95% CI = 0.80–0.99). A fourth pattern of mid-day plus night-time activity showed no relation (HR = 1.02, 95% CI = 0.88–1.19). Our results were consistent across various sensitivity analyses, including the restriction to never smokers, the exclusion of the first 2 years of follow-up, and the adjustment for shift work.
Conclusions
A pattern of early- plus late-day activity is related to reduced colorectal cancer risk, beyond the benefits of overall activity. Further research is needed to confirm the role of activity timing in colorectal cancer prevention.
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Strengths and limitations
The primary strength of our study lies in its novel exploration of diurnal activity timing in relation to colorectal cancer using fPCA. This method is free from pre-set assumptions about data structure, and it efficiently reduces data complexity and captures essential variation while maintaining the continuous nature of the data, rendering it ideal for understanding nuanced trends in time-series of raw accelerometry data. Capturing the entire range of acceleration signals provided us with a detailed perspective on overall activity timing. Another significant asset of our study is its large sample size, allowing us to perform a wide range of informative sub-analyses, confirming the robustness of our findings.
A limitation is our focus on hourly acceleration averages without distinguishing activity types or intensities, potentially masking certain aspects affecting colorectal cancer risk, such as the benefits of short bursts of vigorous activity [55]. The accelerometry data lacked contextual details, limiting insights into how different environments in which activity occurred could influence the impact of physical activity on colorectal cancer. Additionally, we did not examine whether chronotype or sleep patterns modified the association between activity timing and colorectal cancer. Case numbers were relatively low, especially in subgroup analyses, potentially masking true effects. UK Biobank is susceptible to selection bias [56] and the accelerometer subpopulation studied may exhibit healthy volunteer bias given the relatively high levels of activity [57, 58]. Finally, translating the fPCA findings into public health messages is challenging given the complexity of these analytic approaches. However, our results support physical activity recommendations that “every move counts.”
