Physical and psychological health among breast cancer survivors: Interactions with sedentary behaviour and physical activity

Background: Supportive care interventions are needed to reduce the chronic and late-appearing effects of breast cancer treatments. Reducing sedentary behaviour (SED) may be one promising strategy given the unique health benefits of low SED that are distinct from beneficial effects of moderate-to-vigorous intensity physical activity (MVPA).

Objectives: To examine the associations between SED and the late-effects symptoms of pain, fatigue and dysphoria among breast cancer survivors (BCS), and how these associations may be moderated by MVPA.

Methods: One hundred and ninety-nine BCS provided initial baseline data 3 to 4 months post-systemic treatment, as part of the Life After Breast Cancer: Moving On longitudinal study. Pain, fatigue, and dysphoria symptoms were assessed on three non-consecutive days during a 7-day period using validated self-report questionnaires. Objective measures of MVPA and SED (i.e., sitting time) were assessed by GT3X accelerometers over the same period. Daily minutes of sitting time and MVPA were estimated. Self-reported demographic and medical variables were collected.

Results: In hierarchical multiple regression analyses controlling for treatment and demographic covariates, the interaction effect of MVPA by SED was significantly associated with pain (p=.02), fatigue (p=.01), and dysphoria (p=.03). Follow-up simple slopes analyses demonstrated that among BCS with lower levels of MVPA, higher levels of SED significantly predicted higher levels of fatigue (p<.001), and higher levels of pain (p=.06). Among women with higher levels of MVPA, higher levels of SED predicted lower levels of dysphoria (p=.08).

Conclusions: Prolonged sitting time coupled with lower levels of MVPA contribute to higher levels of fatigue and pain among BCS.

What are the implications of your research on practice or policy? These findings will inform health promotion interventions and policies to target positive lifestyle changes for symptom management and quality of life among BCS.