Longer Sitting Time Linked to 9 Percent Higher Risk of Cancer Death: Study - Video

Sitting for long, uninterrupted periods may be more harmful than simply spending a lot of time sitting, according to new research linking prolonged sitting with cancer risk.

The study, published in PLOS Medicine, included 91,292 people from the UK Biobank. Participants wore activity monitors for seven days, and researchers followed them for an average of more than 12 years.

Researchers found that every additional hour spent sitting for long periods was linked to a 9% higher risk of dying from cancer. Long periods of sitting were defined as sitting for at least 30 minutes at a time, with most of that period spent inactive.

People who spent more time in these prolonged sitting periods also had higher risks of developing cancer overall, as well as cancers linked to obesity and type 2 diabetes.

However, regularly breaking up sitting time appeared to be linked with better outcomes. Researchers estimated that replacing one hour of prolonged sitting each day with light physical activity was associated with a 12% lower risk of dying from cancer.

The findings suggest that it may not only be important how much time people spend sitting, but also how that time is spread throughout the day. Getting up regularly and moving for short periods could help reduce long stretches of inactivity.

However, the study does not prove that prolonged sitting directly causes cancer. It was an observational study, meaning researchers looked at patterns rather than testing whether reducing sitting prevents cancer.

The researchers said the findings highlight the importance of adding movement throughout the day, even for people who exercise regularly. Simple habits such as standing up, taking short walks or regularly breaking up sitting time may be helpful, although further studies are needed to confirm whether these changes can directly reduce cancer risk.

REFERENCE: Ziyi Zhou, Stewart G. et al.; Accelerometry-measured prolonged and interrupted sedentary behavior and cancer incidence and mortality: A cohort study of 91,292 UK Biobank participants. PLOS Medicine, 2026; 23 (7): e1004767 DOI: 10.1371/journal.pmed.1004767