Accelerometer-measured physical activity, sedentary behavior, and mortality among cancer survivors: the Women’s Health Accelerometry Collaboration

BACKGROUND: Data on prospective associations of accelerometer-measured physical activity (PA), sedentary behavior (SB), and mortality among cancer survivors are lacking. Our study examined accelerometer-measured daily PA (including light, moderate-to-vigorous PA [MVPA], total PA, and steps), SB (sitting time and mean bout duration), and mortality among cancer survivors in the Women's Health Accelerometry Collaboration (WHAC). METHODS: Postmenopausal women in WHAC who reported a cancer diagnosis ≥1 year prior to wearing an ActiGraph GT3X+ on the hip for ≥4 of 7 days from 2011-2015 were included. Outcomes included all-cause, cancer, and cardiovascular disease (CVD) mortality. Covariate-adjusted Cox regression estimated hazard ratios (HRs) and 95% confidence intervals (CIs) for each PA and SB measure in association with mortality. RESULTS: Overall, 2,479 cancer survivors (mean [SD] age, 74.2 [6.7] years) were followed for 8.3 years. For all-cause mortality (n = 594 cases), every 78.1 min/day in light PA, 96.5 min/day in total PA, 102.2 min/day in sitting time, and 4.8 min in sitting bout duration had HRs (95%CIs) of 0.92 (0.84-1.01), 0.89 (0.80-0.98), 1.12 (1.02-1.24) and 1.04 (0.96-1.12), respectively. Linear associations for cancer mortality (n = 168) and CVD mortality (n = 109) were not statistically significant except for steps (HR per 2,469 steps/day=0.66, 95%CI: 0.45-0.96) and sitting time (HR = 1.30, 95%CI: 1.02-1.67) for CVD mortality. Nonlinear associations showed benefits of MVPA (for all-cause and CVD mortality) and steps (all-cause mortality only) maximized around 60 min/day and 5,000 steps/day, respectively. CONCLUSIONS: Among postmenopausal cancer survivors, higher PA and lower SB was associated with reduced hazards of all-cause and CVD mortality.