Abstract
PURPOSE: Moderate-to-vigorous physical activity (MVPA) can improve the quality of life (QoL) for breast cancer survivors (BCS), yet, most do not achieve 150 + weekly minutes of MVPA. This study investigated moderators of response to a physical activity (PA) behavior change intervention for BCS. METHODS: BCS (N = 222) were randomized to the 3-month intervention (BEAT Cancer) or usual care. Measurements occurred at baseline, post-intervention, and 3 months post-intervention. Measures included accelerometry, self-reported MVPA, and Functional Assessment of Cancer Therapy (FACT-General, FACT-Breast, physical well-being (PWB), social well-being (SWB), emotional well-being (EWB), functional well-being (FWB), additional concerns (AC), and Trial Outcome Index (TOI)). RESULTS: Adjusted linear mixed-model analyses indicated individuals ≤ 24 months post-diagnosis and who were single reported smaller increases in weekly self-reported MVPA than those > 24 months (44.07 vs 111.93) and partnered (- 16.24 vs. 49.16 min), all p < 0.05. As for QoL, participants < 12 months post-diagnosis who received chemotherapy experienced smaller improvements than those ≥ 12 months in FACT-General, FACT-Breast, PWB, and SWB scores. Survivors with a history of chemotherapy had smaller improvements in FACT-General, FACT-Breast, PWB, SWB, TOI, and AC scores, all p < 0.05. CONCLUSION: These findings indicate that being < 2 years post-diagnosis, single, and prior chemotherapy may limit MVPA and QOL responses to a PA intervention. Further studies are needed to determine if and/or what additional PA supports and resources these subgroups of BCS might find beneficial and effective. TRIAL REGISTRATION: ClinicalTrials.gov number: NCT00929617.