Amount And Intensity Of Daily Physical Activity Measured By Accelerometers And Risk Of Incident Cancer In The Uk Biobank Prospective Cohort

The influence of total daily and light intensity activity on cancer risk remains unclear, as most existing knowledge is from studies on self-reported leisure-time activities of moderate-vigorous intensity. PURPOSE: To investigate associations between total daily physical activity and activity intensity on incident cancer risk. METHODS: Prospective analysis of cancer-free UK Biobank participants wearing wrist-based accelerometers for 7-days, followed for cancer incidence through national registries (mean follow-up 5.8 yrs (SD = 1.3)). Machine learning models derived total activity (average acceleration), behavior time, step counts and peak 30-minute cadence. Cox proportional hazards regression estimated hazard ratios (HR) and 95% confidence intervals (CI). The primary outcome was a composite of 13 cancers previously associated with low physical activity (bladder, breast, colon, endometrial, esophageal adenocarcinoma, gastric cardia, head and neck, kidney, liver, lung, myeloid leukemia, myeloma, and rectum). Reducing sedentary time in favor of increased activity time was examined using compositional data analysis. Models adjusted for age, sex, ethnicity, smoking, alcohol, education, deprivation, and reproductive factors. RESULTS: Among 86,556 participants (mean age 62.0 yrs (SD = 7.9) at accelerometer wear), 2,669 physical-activity-related cancers occurred. Higher total physical activity was associated with a lower cancer risk (HR1SD = 0.85, [95%CI, 0.81-0.89]). On average, reallocating one hour/day from sedentary behavior to moderate-vigorous physical activity was associated with a lower risk (HR = 0.93, 0.90-0.96), as was reallocating one hour/day to light-intensity physical activity (HR = 0.95, 0.93-0.97). Compared to individuals taking 5,000 daily steps, those taking 9,000 steps had a lower risk of physical-activity-related cancer (HR = 0.82, 0.74-0.90). We found no significant association with peak 30-minute cadence after adjusting for total steps. CONCLUSIONS: Higher total daily activity and less sedentary time, in favour of light and moderate-vigorous intensity activity, were associated with a lower risk of certain cancers. For less active adults, increasing daily step counts by 4,000 may be a practical public health intervention for lowering the risk of some cancers. The funders/sponsors had no role in the design of this study, the analysis and interpretation of the results, or drafting of the manuscript.