Abstract
Introduction: The relationship between physical activity (PA) and sedentary behavior (SB) with mortality among women after a cancer diagnosis is understudied. We examined accelerometer-measured daily PA and SB in relation to all-cause and cardiovascular disease (CVD) mortality among postmenopausal cancer survivors in the Women's Health Accelerometry Collaboration (WHAC).
Methods: This study included 2,616 WHAC participants who reported a cancer diagnosis prior to baseline. From 2011-2015, WHAC participants wore an ActiGraph GT3X+ on the hip for ≥10 hours per day for ≥4 of 7 days. Daily accelerometer PA measures included light PA, moderate-to-vigorous PA (MVPA), total PA, and steps. SB measures were total sitting time and mean sitting bout duration. Mortality outcomes were ascertained through 2022. Hazard ratios (HRs) and 95% confidence intervals (CIs) were estimated using multivariable stratified Cox regression for each PA and SB measure in association with all-cause and CVD mortality. Models were adjusted for age, race/ethnicity, education, smoking status, alcohol use, general health, postmenopausal hormone use, diabetes, CVD, BMI, physical function, cancer type, and years since cancer diagnosis. Evidence of non-linearity was explored using restricted cubic splines.
Results: Overall, the 2,616 cancer survivors (mean [Standard Deviation, SD] age, 74.3 [6.7] years) were followed for a mean of 8.2 years. For all-cause mortality (n=646 cases), 1-SD increments in light PA (78.3 min/day), total PA (96.7 min/day) sitting time (102.3 min/day) and sitting bout duration (4.7 min/bout) were associated with adjusted HRs (95% CIs) of 0.92 (0.84, 1.00), 0.89 (0.80, 0.98), 1.12 (1.02, 1.23), and 1.05 (0.97, 1.13), respectively. Statistically significant nonlinear associations were observed for MVPA and steps (Figure). The dose-response curve for steps shows the maximal benefit occurs around 5,000 steps/day before leveling off. The maximal mortality benefit for MVPA was near 50 min/day. For CVD mortality (n=119 cases), 1-SD increments in MVPA (32.9 min/day) and steps (2470 steps/day) were associated with adjusted HRs (95% CIs) of 0.59 (0.41, 0.84) and 0.64 (0.45, 0.93), respectively, while associations for light PA, total PA, and SBs were not significant.
Conclusions: Among postmenopausal cancer survivors, higher PA and lower sitting time are associated with reduced risk of all-cause mortality, while more MVPA and steps were associated with reduced CVD mortality risk.