Early-stage breast cancer survivors have a heightened risk of cardiovascular disease (CVD) and CVD-related mortality due to shared risk factors for breast cancer and CVD and also the direct and indirect cardiovascular toxicity of breast cancer therapies. On average, the cardiorespiratory fitness (CRF) of breast cancer survivors is 17% below healthy adults even prior to receiving breast cancer therapies and decreases an additional 8%-16% after receiving these therapies. Current practice guidelines to address the risk of CVD in these patients focus on the prescription of pharmacologic therapies, but a more holistic approach might also incorporate exercise training to reduce CVD risk. In 2019, The American Heart Association (AHA) released a Scientific Statement to introduce the concept of cardio-oncology rehabilitation (CORE) to help manage CVD risk in cancer patients. The statement called for further research into this concept to help better create a structure for this type of rehabilitation and to determine if the services were clinically warranted.

Since the release of the AHA statement on cardio-oncology, additional studies have focused on the benefits of cardio-oncology and exercise training for breast cancer survivors. A new article published in the January 2024 issue of JCRP entitled “A Review on the Role of Exercise Training to Prevent a Decline in Cardiorespiratory Fitness and Cardiac Function in Breast Cancer Survivors” looks to examine the current research on this topic to determine the possible benefits of incorporating exercise training into therapies offered to breast cancer survivors.

The author group, led by Dr. Steven Foulkes with support from Dr. André La Gerche and Dr. Mark Haykowsky, conducted a literature review of systematic reviews, meta analyses, randomized and non-randomized controlled trials and single-arm trials on the topic to better understand the current evidence base for exercise therapy for breast cancer survivors and to identify areas for future research.

This analysis of the existing literature confirms that exercise training and CORE in breast cancer survivors is promising, feasible, safe and can result in improvements in CRF, but more work is needed to create a program tailored to the needs of breast cancer survivors. Additionally, while exercise testing did lead to  improvements in CRF, significant changes in echocardiographic parameters like resting left ventricular ejection fraction and global longitudinal strain were not noted.

This current research indicates that adaptations to standard rehabilitation programs may be needed to best serve the breast cancer survivor patient population. In studies that were specific to the impact of exercise training on breast cancer survivors, the duration of exercise training ranged between 3 and 8 months with at least 2-4 sessions per week, and CRF tended to increase as duration and intensity of the programs increased. In terms of exercise prescription, the current research suggests that a multicomponent approach including high intensity exercise training (HIIT), moderate continuous training, resistance training and step-down models may be best for this population especially when paired with extended intervention periods. Chemotherapy can also cause anemia and elevated heart rates, which could lead to an underestimation of exercise dose using standard exercise prescription methods. Clinicians can combat this by accounting for fluctuations in heart rates and using subjective intensity methods to help set an appropriate exercise prescription. Additionally, chemotherapy-periodized exercise, where exercise is adjusted down during the first week after chemotherapy to account for acute chemotherapy side effects, can help with attendance and adherence.

Although more research is needed to fully understand the benefits of CORE and the best ways to deliver CORE in breast cancer survivors, the authors conclude that exercise-based CORE should be considered in breast cancer survivors at increased CVD risk and impaired CRF.

A visual abstract from the author group that outlines the results of the study can be viewed below, and the full article can be viewed by accessing JCRP through the AACVPR Member portal on the AACVPR website.