Changes In Health-related Fitness After Breast Cancer Treatment In The AMBER Cohort Study

Early-stage breast cancer patients often receive multimodal cancer treatments consisting of various combinations of surgery, chemotherapy, radiotherapy, targeted therapy, and hormone therapy. Limited data are available on how these treatment modalities affect different domains of health-related fitness (HRF). PURPOSE: The present study reports the associations between different breast cancer treatment modalities and 1-year changes in HRF. METHODS: Newly diagnosed early-stage breast cancer patients were recruited between 2012-2019 in Edmonton and Calgary, Canada for the Alberta Moving Beyond Breast Cancer (AMBER) cohort study. Participants completed HRF assessments within 90 days of diagnosis and one year after diagnosis including cardiorespiratory fitness (VO2peak treadmill test), muscular fitness (upper and lower body muscular strength and endurance), and body composition (DXA scan). Treatment data were abstracted from electronic medical records. Analysis of covariance examined changes in HRF by different treatment modalities and combinations. RESULTS: AMBER included 1,528 participants of which 41.4% had a mastectomy, 58.2% chemotherapy, 74.3% radiotherapy, 81.6% hormone therapy, and 16% targeted therapy. Receiving chemotherapy was associated with a decrease in upper body strength (p = 0.048), fat-free mass (p = 0.049), and bone mineral density (p < 0.001). Receiving radiotherapy was associated with a decrease in relative VO2peak (p = 0.025) and bone mineral density (p < 0.001). Having a mastectomy was linked to a reduction in upper body endurance (p = 0.037). Receiving hormone therapy was associated with reductions in lower body strength (p = 0.033), lean mass (p = 0.001), and fat-free mass (p = 0.002). Receiving targeted therapy was associated with a decline in relative VO2peak (p = 0.017). The combination of receiving all 5 treatment modalities (n = 55) was associated with increased body weight (p = 0.043) and decreased bone mineral density (p = 0.023). CONCLUSIONS: Different cancer treatments uniquely impact different HRF domains in early-stage breast cancer. Understanding the changes in HRF based on individual and combinations of treatment modalities will inform tailored exercise interventions during and after breast cancer treatments. Team Grant (#107534), Project Grant (#155952), and Foundation Grant (#159927) from the Canadian Institutes of Health Research, Canada Research Chairs Program, Alberta Innovates Health Senior Scholar Award, Alberta Cancer Foundation Weekend to End Women's Cancers Breast Cancer Chair