Special attention to reducing the risk of cardiovascular disease should be a priority for long-term care of patients with breast cancer.
Jean-Bernard Durand MD, FACC, FACP, FHFSA, FAHA
Special attention to reducing the risk of cardiovascular disease should be a priority for long-term care of patients with breast cancer, according to Jean-Bernard Durand MD, FACC, FACP, FHFSA, FAHA.1
"The mortality for breast cancer continues to go down, but what women are going to be faced with if they do not have a recurrence (is that) their number one cause of death is cardiovascular disease," Durand, medical director of Cardiomyopathy Services, and director of cardiovascular genetics research and the Cardiology Fellowship Program at The University of Texas MD Anderson Cancer Center. "We have to do a much better job of managing their modifiable risk factors and comorbid conditions."
Physical activity and avoidance of weight gain are 2 important factors in reducing recurrence and mortality in patients with breast cancer. At the time of diagnosis, patients with early-breast cancer may already be at a heightened risk of developing cardiovascular disease. Adjuvant therapies, surgery, and radiation are associated with adverse effects on the cardiovascular system.
A patient's cardiovascular reserve could take a hit with treatments in combination with indirect effects, such as lifestyle changes that include physical inactivity and changes in body composition, leaving a patient more susceptible to further cardiovascular damage and premature mortality.2
Cardiorespiratory Fitness in Patients With Breast Cancer
Cardiorespiratory fitness is an index of functional capacity of the heart and lungs and reflects the efficiency of oxygen uptake, transport, and utilization in the muscles. "It is an excellent surrogate of exercise dose and a reproducible measurement," said Durand.
In a study of 248 patients with breast cancer, the prognostic significance of cardiopulmonary function was assessed as measured by peak oxygen consumption (VO[2peak]). Patients with breast cancer represented 4 cross-sectional cohorts: (1) before, (2) during, and (3) after adjuvant therapy for nonmetastatic disease; and (4) during therapy in metastatic disease. A cardiopulmonary exercise test (CPET) with expired gas analysis was used to assess VO(2peak).3
Despite normal cardiac function (defined as resting measurement of left ventricular ejection function ≥50%), women with breast cancer demonstrated marked impairments in cardiopulmonary function. VO(2peak) was, on average, 27% less than that of age-matched sedentary but otherwise healthy women without a history of breast cancer. The impairment in VO(2peak) during primary adjuvant chemotherapy was 31% less than that of healthy sedentary women and 33% in those patients with metastatic disease.
Improved cardiopulmonary function is possible with the introduction of exercise training programs across the breast cancer continuum. A meta-analysis of 6 studies involving 571 adult patients with cancer examined the effects of supervised exercise training (n = 344) versus nonexercise (n = 227) on measurement of VO(2peak). Intervention lengths were in the range of 8-24 weeks. In all studies, exercise was prescribed 3 times per week and session duration ranged 14-45 minutes. Exercise training was associated with a statistically significant increase in VO(2peak) of 2.90 ml.kg-1.min-1 (95% CI, 1.16-4.64) translating to an improvement from baseline to postintervention of 15% favoring exercise.4
Introducing Exercise Programs in the Clinic
By providing regimens for exercise, clinicians can curb risk factors associated with cardiovascular mortality. Durand noted that the MD Anderson Healthy Heart Program takes a multidisciplinary approach to improve patient outcomes. The team includes physicians, exercise physiologists, health educators, dietitians, and nurses.5
"The Healthy Heart Program helps patients improve their overall fitness and heart health," said Durand. "Our staff and the cardiologists will provide patients with a personalized exercise boutique and patients also receive information regarding heart disease and ways to improve heart health over the course of their lives."
The patient undergoes a preliminary evaluation that includes a screening exam and a treadmill test to determine their maximal oxygen consumption. "This will allow us to assess cardiopulmonary safety and determine the exercise dose, as well as compare their fitness level relative to their age and sex," Durand explained. Standard of care assessment is also conducted and includes assessing the impact of prior cancer treatment on heart health, cholesterol levels, risk of hypertension or high blood pressure, risk of diabetes, body weight and waist measurements, family history on heart health, and, if needed, smoking cessation.
Developing Prescribed Programs
"One difficulty is trying to explain the metabolic equivalent task [METs] to patients," Durand noted. "The Harvard School of Public Health does a great job of breaking this down into light, moderate, and vigorous activity. We like to shoot for the [moderate] area of 3 to 6 METs," he noted.6
In a study by Jones et al that that assessed leisure-time recreational physical activity, patients whose exercise program consisted of ≥ 9 MET hours per week was associated with a 23% reduction in the risk of cardiovascular events irrespective of age, cardiovascular disease risk factors at diagnosis, menopausal status, and type of anticancer therapy.7
Patient biases also play into difficulties for prescribing patients to exercise programs. "We have biases and the patient has biases. The patient bias is that you are expecting them to get to a gym, get a personal trainer, and do exercise every single day and that could not be farther from the truth," Durand said. "I like to recommend the buddy program, finding a neighbor or friend who will walk with you at a brisk pace, and set up a schedule that you will do this as a team."
On the importance of personalizing exercise prescriptions, Durand noted that "not everyone of your patients are going to be able to do the same thing," and recommended follow up visits with exercise physiologists and other identified specialists as needed to complete the spectrum of care. "[Clinicians] need to have a team of individuals where you can pick up the phone or you can text them and say, 'I want to send this patient for an exercise prescription with specific goals.'"