Effects of exercise during chemotherapy for breast cancer on patient-reported outcomes: Secondary data analysis of a randomized controlled trial

Background: Breast cancer is associated with poorer patient-reported outcomes (PROs) during treatment. Interventions to improve PROs are needed to reduce the burden associated with breast cancer. We tested the effects of an aerobic exercise intervention initiated during chemotherapy for breast cancer (EX) compared to usual care (wait-list control condition; UC) on PROs (cancer-related fatigue [CRF], general and disease-specific quality of life [QoL]) post-intervention. Methods: This study involved secondary analysis of data from the ACTIVATE trial – a two-arm, two-centre randomized controlled trial conducted in Ottawa and Vancouver. Women (N=57; Mage=48.8±10 years) diagnosed with stage I-III breast cancer and awaiting chemotherapy were randomized to aerobic exercise initiated with chemotherapy (nEX=28) or usual care during chemotherapy with aerobic exercise after chemotherapy completion (nUC=29). The intervention lasted 12-24 weeks and involved supervised aerobic training and at-home exercise. PROs were considered secondary outcomes and assessed via generic and disease-specific questionnaires. Analysis of covariance adjusting for baseline scores and pre-specified covariates (age, education, self-reported exercise) was used to compare PROs between groups post-intervention (commensurate with chemotherapy completion). Results: Post-intervention, EX reported lower CRF and higher QoL than UC; however, differences were not significant for any of the PROs after adjusting for baseline scores and covariates (p-values >0.05). Conclusions: Although observing that aerobic exercise during chemotherapy for breast cancer did not significantly improve CRF and QoL in the short-term compared to UC is surprising considering findings from previous reviews, we will discuss ideas that may explain these results and that could direct future research and intervention design.