Accelerometry-measured prolonged and interrupted sedentary behavior and cancer incidence and mortality: A cohort study of 91,292 UK Biobank participants | PLOS Medicine

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Abstract

Background

Current sedentary behavior (SB) guidelines primarily emphasize total time spent sedentary. We explored differences between interrupted and prolonged SB in relation to a range of cancer outcomes.

Methods and findings

This study included 91,292 UK Biobank participants with valid accelerometer data. Participants were followed for a median of 12.38 years (interquartile range 11.56–13.15 years). A two-step approach based on a random forest model was used to classify SB. Multivariable Cox proportional hazards models were applied to overall incident cancers and cancer deaths, plus obesity-related and type-2 diabetes-related cancers, and 23 site-specific cancers. Models were adjusted for demographic, socioeconomic, lifestyle, dietary, and health-status factors, including age, ethnicity, deprivation, education, smoking, alcohol intake, diet, and morbidity count. Isotemporal substitution models were used to estimate the associated cancer risk when replacing prolonged SB with intermittent SB, or physical activity (PA). After adjusting for sociodemographic and lifestyle factors, each additional hour of prolonged SB was associated with a higher risk of overall cancer mortality (hazard ratio [HR] HR1hour 1.09; 95% confidence interval [CI] [1.06, 1.11]; p LPA 0.88; 95% CI [0.79, 0.99]; p = 0.033) was associated with lower risk of overall cancer mortality. Similarly, replacing 30 min per day of prolonged SB with moderate PA (HRMPA 0.92; 95% CI [0.86, 0.99]; p = 0.024) was associated with a lower risk of overall cancer mortality. The main methodological limitations were observational design, residual confounding, healthy volunteer bias, and measurement imprecision due to having only 7 days of accelerometer wear.

Conclusion

Cancer risk associated with SB is specific to prolonged SB. Replacing prolonged SB physical activity is associated with lower cancer risk.

Author summary

Why was this study done?

Previous studies have shown that spending more total time on sedentary behavior, such as sitting or reclining while awake, is linked to poorer health outcomes.

Some evidence suggests that replacing sedentary time with physical activity (PA) may lower the risk of cancer death, but less is known about whether the pattern of sedentary time matters.

This study was done to examine whether long, uninterrupted periods of sedentary behavior and shorter, interrupted periods of sedentary behavior are differently associated with cancer risk.

What did the researchers do and find?

We studied 91,292 UK Biobank participants with valid activity monitor data and followed them for a median of 12.38 years.

Each additional hour per day of prolonged sedentary behavior was associated with a 10% higher hazard of cancer death, whereas each additional hour of interrupted sedentary behavior was associated with a 19% lower hazard of cancer death.

Replacing prolonged sedentary behavior with PA was associated with a lower risk of cancer death: a 12% lower hazard when 1 hour per day was replaced with light PA, an 8% lower hazard when 30 min per day was replaced with moderate PA, and 22% lower hazard when 5 min per day was replaced with vigorous PA.

What do these findings mean?

These findings suggest that not only the total amount of sedentary time, but also how sedentary time is accumulated, may be important for cancer risk.

Reducing long, uninterrupted periods of sedentary behavior and replacing them with PA, even those with light intensity, may be a practical target for future interventions.

These findings should be interpreted with caution because the study cannot prove causality, UK Biobank volunteers may not represent the wider population, and the activity monitor captured behavior only during a limited period without showing the context of sedentary behavior, such as work, television viewing, or driving.

Citation: Zhou Z, Trost SG, Ryde GC, Parra-Soto S, Fang Z, Xu C, et al. (2026) Accelerometry-measured prolonged and interrupted sedentary behavior and cancer incidence and mortality: A cohort study of 91,292 UK Biobank participants. PLoS Med 23(7):<br>e1004767.

https://doi.org/10.1371/journal.pmed.1004767<br>Academic Editor: Steven C. Moore, National Cancer Institute, UNITED STATES OF AMERICA<br>Received: September 11, 2025; Accepted: May 29, 2026; Published: July 2, 2026<br>Copyright: © 2026 Zhou et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.<br>Data Availability: This study was conducted using third-party data from the UK Biobank (www.ukbiobank.ac.uk) under...