Background: Evidence is suggestive of sedentary behaviour being associated with an increased risk of endometrial cancer, but the evidence base is too limited to draw any conclusions for other cancers. The aim of the study was to investigate the association between recreational screen time and site-specific cancer risk.
Methods: We analysed data from the prospective UK Biobank cohort study. Cox proportional hazards models were used to estimate hazard ratios (HRs) and 95% confidence intervals (CIs) for associations between daily recreational screen time (including television (TV) viewing time, computer use time and total screen time) and site-specific cancer risk. Partition models and isotemporal substitution models investigated the impact of substituting recreational screen time with physical activity.
Results: During a mean follow-up of 7.6 years, 28,992 incident cancers were identified among 470,578 adults. A 1-hour increase in daily TV viewing time was associated with higher risks of oropharyngeal, oesophago-gastric and colon cancer in fully adjusted models. Participants who reported ≤1, compared with 1-≤3, hours/day of TV viewing time had lower risks of lung, breast, and oesophago-gastric cancer. Findings were inconsistent for daily recreational computer use and daily total recreational screen time. The majority of observed associations were small, and were attenuated after excluding cancers diagnosed within the first two years of follow-up, except for oesophago-gastric and colon cancers (HR 1.05, 95% CI: 1.01-1.10; and HR 1.04, 95% CI: 1.01-1.07 per 1-hour increase in daily TV viewing time, respectively). However, isotemporal substitution models showed reduced risk of some site-specific (oropharyngeal, lung, breast and colorectal) cancers when replacing 1-hour/day of TV viewing with 1-hour of moderate-intensity physical activity or walking.
Conclusions: Our findings show that daily recreational screen time, particularly TV viewing, was associated with small increased risks of oesophago-gastric and colon cancer. Replacing 1-hour/day of TV viewing with 1-hour of moderate-intensity physical activity or walking was associated with lower risk of oropharyngeal, lung, breast and colorectal cancers. Further research from other large prospective cohort studies is required, while mechanistic research is warranted to enhance the biological plausibility of these findings.
A multi-level approach to better understand the association between physical activity and sedentary behaviour, and cancer risk
Our aims are to investigate physical activity behaviour and sedentary behaviour, and cancer risk, including better estimations of the magnitude of risk by different cancer sites.
Specifically, we aim:
1) To evaluate correlations between physical activity and sedentary behaviour data and relevant biomarkers related to physical activity/sedentary behaviour and cancer
2) To analyse the association between physical activity and sedentary behaviour data and relevant genetic variants identified within GWAS data and cancer risk.
3) To analyse factors related to the built environment, physical activity, sedentary behaviour, and cancer risk. The aim of UK Biobank is to improve the prevention, diagnosis and treatment of serious and life-threatening illnesses, including cancer. The proposed research will elucidate the role of physical activity and sedentary behaviour in cancer prevention. The study will provide insight into biological mechanisms by which physical activity and sedentary behaviour may impact on different cancer sites, the role of individual modifiable and non-modifiable characteristics, and built environment factors in influencing the association between physical activity, sedentary behaviour, and cancer risk. Results will help inform the development of future physical activity/sedentary behaviour related interventions for cancer prevention. Linkage between UK Biobank and cancer registries provides information on cohort members who have been diagnosed with cancers. Using appropriate statistical techniques, we will compare physical activity and sedentary behaviour amongst cohort members who have developed cancer with those who have not developed these cancers, examining questionnaire and accelerometer (measure of physical activity/sedentary behaviour) data. We will also evaluate the associations with relevant biomarkers from the panel of blood/urinary markers and genetic analyses to be undertaken on all cohort members. The full cohort will be included in all analyses to be undertaken.
|Lead investigator:||Dr Ruth Hunter|
|Lead institution:||Queen's University Belfast|