Associations of grip strength and body mass index with cancer mortality in 413,338 adults: The UK Biobank study

Abstract

Background: There is compelling evidence that, independent of adiposity, higher aerobic fitness is associated with lower risks of cancer. However, little is known about whether cancer risk is lower with higher muscle strength, independent of adiposity. Objective: The aim of this study was to investigate the associations between grip strength (GS), body mass index (BMI), and total and 11 site-specific cancer mortality outcomes.Methods: The UK Biobank data is an ongoing prospective cohort containing >500,000 adults aged 40-69 years at baseline (2006-2010). The average GS value of both hands was divided by fat-free mass to account for differences inbody size. Age-and sex-specific cut-points were used to generate three categories of GS. BMI was used as an indicator of adiposity. Cox regression models using age as the underlying time scale were performed to estimate associations between GS, BMI and each cancer mortality type. Models were adjusted for potential confounders. Results: Data from 413,338 participants were used in the present analyses. Over a median 7.0-year follow-up period, a total of 5,052 cancer deaths were accrued. Compared with the lowest GS group, the highest GS group showed a 12% lower hazard of total cancer mortality (Hazard Ratio [HR]: 0.88; 95% CI: 0.82-0.95) after adjusting for BMI as well as confounders. In obese individuals (BMI>30 kg/m2), the middle category of GS was associated with a 14% lower hazard of total cancer mortality (HR: 0.86; 95% CI: 0.76-0.97) compared with the lowest. The highest GS group showed reduced risks of liver (HR 0.57; 95% CI 0.38-0.85), and bladder cancers (HR 0.39; 95% CI 0.22-0.68), compared with thelowest. While higher GS was associated with lower risks of liver, ovary, blood and bladder cancers in normal weight (only for ovary and blood cancers) or overweight individuals, none of the associations between GS and 11 site-specific cancers were statistically significant in obese individuals (p-values >0.05 for interaction for all 11 site-specific cancers).Conclusions: Individuals with higher GS may have lower risks of total, liver and bladder cancer mortality, independent of BMI. In obese individuals, higher GS may be protective against only total cancer mortality.