Associations of device-measured physical activity and sedentary time with quality of life and fatigue in newly diagnosed breast cancer patients: Baseline results from the AMBER cohort study

Background: This study examined associations of device-measured physical activity and sedentary time with quality of life (QOL) and fatigue in newly diagnosed breast cancer patients in the Alberta Moving Beyond Breast Cancer (AMBER) cohort study. Methods: After diagnosis, 1409 participants completed the SF-36 version 2 and the Fatigue Scale, wore an ActiGraph device on their right hip to measure physical activity, and an activPAL device on their thigh to measure sedentary time (sitting/lying) and steps. ActiGraph data was analyzed using a hybrid machine learning method (R Sojourn package, Soj3x) and activPAL data were analyzed using activPAL algorithms (PAL Software version 8). Quantile regression was used to examine cross-sectional associations of QOL and fatigue with steps, physical activity, and sedentary hours at the 25th, 50th, and 75th percentiles of the QOL and fatigue distributions. Results: Total daily moderate and vigorous physical activity (MVPA) hours was positively associated with better physical QOL at the 25th (β = 2.14, p = <.001), 50th (β = 1.98, p = <.001), and 75th percentiles (β = 1.25, p =.003); better mental QOL at the 25th (β = 1.73, p =.05) and 50th percentiles (β = 1.07, p =.03); and less fatigue at the 25th (β = 4.44, p <.001), 50th (β = 3.08, p = <.001), and 75th percentiles (β = 1.51, p = <.001). Similar patterns of associations were observed for daily steps. Total sedentary hours was associated with worse fatigue at the 25th (β = −0.58, p =.05), 50th (β = −0.39, p =.06), and 75th percentiles (β = −0.24, p =.02). Sedentary hours were not associated with physical or mental QOL. Conclusions: MVPA and steps were associated with better physical and mental QOL and less fatigue in newly diagnosed breast cancer patients. Higher sedentary time was associated with greater fatigue symptoms.