Associations of Physical Activity With Breast Cancer Risk: Findings From the UK Biobank Prospective Cohort Study.

PURPOSE: Although physical activity (PA) has been consistently associated with breast cancer, existing evidence is limited to self-reported physical activity, which is prone to dilution bias. Therefore, this aims to examine the associations of device-measured PA domains with breast cancer risk and whether it differs by menopausal status. METHODS: Prospective cohort study. Data from 48,286 women from the UK Biobank cohort were analyzed. A wrist triaxial accelerometer was used to collect physical activity data for light, moderate, vigorous, moderate to vigorous, and total PA. Cox proportional models were performed to examine the association between PA domains, menopausal status, and breast cancer risk. RESULTS: Eight hundred thirty-six breast cancer cases were diagnosed during a median of 5.4 years (interquartile range: 4.7-5.9). For total PA, those in the most active quartile had a 26% lower risk of breast cancer (Hazard ratio [HR]: 0.74; 95% confidence interval [CI], 0.61-0.91) compared with those least active. Similar results were observed for light PA (HR: 0.79; 95% CI, 0.64-0.96), and moderate to vigorous PA (HR: 0.78; 95% CI, 0.64-0.96). However, moderate PA (HR: 0.73; 95% CI, 0.44-1.19) and vigorous PA (HR: 0.77; 95% CI, 0.56-1.05) was nonsignificant. No evidence of interaction between PA domains and menopause status was found (P > .10). CONCLUSION: High levels of PA are associated with a lower risk of breast cancer with similar magnitude of associations observed across different intensity domains.

Associations Between Relative Grip Strength and the Risk of 15 Cancer Sites.

INTRODUCTION: Grip strength is the most commonly used muscle strength proxy in clinical research. However, evidence regarding the associations of grip strength with cancer has been mainly restricted to overall cancer risk. Therefore, this study aims to evaluate the associations between grip strength relative to BMI and 15 cancer sites as well as with all-cause cancer mortality. METHODS: A total of 445,555 participants (53.8% women, mean age=56.3 years) were recruited across the United Kingdom. The association of grip strength relative to BMI (expressed as 1 SD) with incidence and mortality from 15 cancer sites was investigated using Cox proportional hazard models. All analyses were conducted in April 2021. RESULTS: Over an 8.8-year follow-up period, 37,291 patients were diagnosed with cancer, and 11,363 died of it. After covariate adjustment, higher relative grip strength per 1 SD was associated with a lower risk of incident endometrial (hazard ratio=0.76, 95% CI=0.71, 0.81), liver (hazard ratio=0.81, 95% CI=0.74, 0.88), gallbladder (hazard ratio=0.83, 95% CI=0.73, 0.94), kidney (hazard ratio=0.89, 95% CI=0.84, 0.95), and colorectal (hazard ratio=0.94, 95% CI=0.91, 0.98) cancer as well as with lower risk of gallbladder, colorectal, endometrial, liver, and all-cause cancer mortality. CONCLUSIONS: Grip strength relative to BMI was associated with incidence and mortality from endometrial, gallbladder, colorectal, liver, all-cause cancer, and breast and kidney cancer incidence, independent of major confounding factors, including comorbidity, diet, and physical activity.