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Prolonged uninterrupted sitting linked to higher cancer mortality risk, study finds

A study of more than 91,000 UK adults found each additional hour of prolonged sitting was tied to a 9% increase in cancer mortality, while light activity reduced the risk.

Updated Sep 3, 2026 · 08:18 UTC1 reports

The short version

  • A study published in PLOS Medicine analyzed activity data from 91,292 UK Biobank participants over a median follow-up of 12.38 years.
  • Researchers found each extra hour of uninterrupted sedentary behavior lasting at least 30 minutes was associated with a 9% higher risk of cancer death.
  • Replacing one hour of prolonged sedentary time daily with light physical activity was linked to a 12% reduction in cancer mortality.
  • Because the research is observational, it cannot establish a direct causal relationship, and authors note clinical trials are needed.

Key facts

  • A study led by University of Glasgow researchers analyzed 91,292 UK Biobank participants who wore activity trackers for seven days and were followed for a median of 12.38 years.[ScienceDaily]
  • Each additional hour of prolonged sedentary behavior—defined as bouts lasting at least 30 minutes—was associated with a 9% increased risk of cancer mortality, as well as higher rates of overall, obesity-related, and type 2 diabetes-related cancer incidence.[ScienceDaily]
  • Interrupted sedentary behavior showed an inverse pattern, correlating with lower risks across the evaluated cancer outcomes.[ScienceDaily]
  • Statistically substituting one daily hour of prolonged sedentary time with light physical activity was associated with a 12% lower risk of cancer death.[ScienceDaily]

What remains uncertain

  • Due to the observational study design, the research demonstrates statistical association rather than direct causation between uninterrupted sitting and cancer risk.[ScienceDaily]
  • The findings rely on the UK Biobank cohort, which is prone to healthy volunteer bias and tends to be more active than the broader population, and researchers lacked data on the specific contexts of participants' sitting time.[ScienceDaily]

Sources