- Prolonged sedentary behavior (SB), defined as bouts lasting at least 30 minutes with over 90% sedentary time, is associated with higher risks of overall cancer mortality, incidence, obesity-related cancers, and type-2 diabetes-related cancers.
- Interrupted SB (bouts less than 30 minutes or broken by activity) is linked to lower risks for the same cancer outcomes.
- Replacing prolonged SB with physical activity reduces cancer risk: substituting 1 hour/day with light PA lowers cancer mortality risk by 12%, and replacing 30 minutes/day with moderate PA reduces risk by 8%.
- Vigorous PA, even in short durations (e.g., 5 minutes/day), shows the strongest association with reduced cancer incidence.
- The study used accelerometer data from 91,292 UK Biobank participants over a median 12.38-year follow-up, employing machine learning for SB classification.
- No significant interaction was found between SB and obesity status (BMI, waist-to-hip ratio, waist-to-height ratio) for cancer risk associations.
- Limitations include observational design, potential residual confounding, healthy volunteer bias, and limited context (e.g., work vs. leisure) from accelerometer data.