Objectively-Measured Physical Activity in Breast Cancer Patients Undergoing Chemotherapy

Abstract

PURPOSE: To determine the effect of demographic, health, and treatment factors on moderate to vigorous physical activity (MVPA) in breast cancer patients undergoing chemotherapy. METHODS: Breast cancer patients (N=66, Mage= 48.3±10.0 years) undergoing chemotherapy (CT) wore an accelerometer for 24-hours (worn on the hip during the day and wrist while sleeping) for ten consecutive days (3 days pre-, day of, and 6 days post-CT dose) during three treatment phases (beginning, middle and end of chemotherapy). Mixed models were used to assess the effect of demographic, health, and treatment factors on MVPA. We assessed the effect of time point (burst), treatment status (i.e. pre-CT dose v. day of/post-CT dose), burst x treatment status interaction, age, body mass index, education, total number of comorbidities, disease stage, cumulative treatment cycle number, self-reported pre-diagnosis minutes/day of MVPA, weekend v. weekdays, and self-reported health status on daily minutes of MVPA. RESULTS: On average, breast cancer patients engaged in 20.8 minutes/day (95%CI:17.4,24.1) of MVPA across all bursts. Results indicate a significant decrease of 5.0 minutes/day of MVPA(95%CI:-6.5,-3.5) as time point increases, a 4.2 minute/day decrease in MVPA(95%CI:-5.8,-3.2) on day of CT dose or post-CT days compared to pre-CT dose days, a 0.9 minute/day increase in MVPA (95%CI: 0.5,1.3) as treatment cycle number increases, and a 2.2 minute/day increase in MVPA (95%CI:1.1,3.2) on weekends. CONCLUSIONS: Results from the current analysis suggest treatment-related factors, such as treatment day, post-treatment days, and time undergoing chemotherapy, had the greatest effect on MVPA in breast cancer patients, significantly decreasing minutes per day spent in MVPA over time. These results show the importance of tailoring future physical activity interventions to specific treatment factors in order to reduce the decline in MVPA during chemotherapy.