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Exercise during adjuvant breast cancer treatment may improve cardiovascular function
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SAN ANTONIO — A supervised 12-month exercise program improved cardiovascular function among women undergoing adjuvant breast cancer treatment, according to results of the randomized EBBA-II trial presented at San Antonio Breast Cancer Symposium.
All patient subgroups benefitted from physical activity, results showed.
“Our study supports incorporation of supervised and safe clinical exercise programs into breast cancer treatment guidelines,” Inger Thune, MD, PhD, professor and senior consultant in oncology at Oslo University Hospital in Norway, said during a press conference. “Breast cancer patients receiving chemotherapy should be offered [a] tailored exercise program based on assessed pretreatment level of physical function.”
Although breast cancer survival rates have increased, a high percentage of survivors experience declines in cardiovascular function. Cardiovascular disease is a competing cause of death in this patient population, and treatment-induced cardiotoxicity is a significant concern.
Thune and colleagues conducted their trial to determine whether a 12-month exercise program that consisted of endurance and strength training during adjuvant breast cancer therapy could influence patients’ cardiopulmonary function. Investigators aimed to identify the recommended type, intensity and duration of exercise. They also evaluated the safety of the intervention.
The trial included patients aged 18 to 75 years with stage I or stage II breast cancer, no known severe illness (eg, uncontrolled diabetes or heart failure) and no prior cancer.
Researchers randomly assigned 271 patients to a 12-month exercise program tailored based on assessed cardiovascular function. The other 274 patients were assigned to a standard-of-care group for which there were no restrictions.
The physiotherapist-led exercise program — which began 3 weeks after surgery — consisted of two 60-minute group sessions plus 120 minutes of at-home exercise each week. The program included moderate- to high-intensity aerobic, stretching and weight-bearing exercise.
Study participants underwent cardiovascular capacity assessments before surgery, as well as 6 months and 12 months after surgery. The exercise regimen was tailored to study participants based on their maximal oxygen uptake (VO2 max) at baseline.
The exercise and control groups were balanced with regard to age (55.2 years vs. 55.6 years), education, age at menarche, blood pressure, tumor characteristics, surgery type, and percentage of patients who underwent chemotherapy, radiation therapy and endocrine therapy. The groups also were balanced in terms of baseline cardiorespiratory fitness (V02 max, 2.17 L/min vs. 2.22 L/min).
After 6 months, patients in both groups had experienced declines in V02 max from presurgery levels, a finding Thune said is not unexpected in the first few months after surgery. The decrease was greater in the control group than the exercise group (10% vs. 2.7%).
After 12 months, in the overall study population, patients assigned to the exercise program achieved a 0.3% increase in cardiovascular fitness and those assigned to the control program exhibited an 8.9% decrease (P < .001).
Among those who did not undergo chemotherapy, levels increased by 1.6% in the intervention group and decreased by 2.7% in the control group (P < .001).
Cardiovascular fitness levels declined among trial participants who received chemotherapy, but the decline was less pronounced among patients in the exercise group than the control group (0.8% decrease vs. 6.4% decrease; P < .001). Results showed a similar trend among patients who received taxanes (1.4% decrease vs. 7.3% decrease).
In addition to cardiovascular benefits, exercise might help improve quality of life and reduce fatigue, Thune said.
Future research will evaluate whether exercise affects recurrence and metastasis, as well as patients’ metabolic profile and ability to work.
Attenuation of the main effect may have occurred as some patients in the control group might have increased their activity levels on their own, Thune said. However, she cited measurements before, during and after treatment, as well as a 70% adherence rate, as study strengths. – by Mark Leiser
Reference:
Thune I, et al. Abstract GS5-02. Presented at: San Antonio Breast Cancer Symposium; Dec. 4-8, 2018; San Antonio.
Disclosure:
The Norwegian Research Council, Norwegian Health Authority, Oslo University Hospital, St. Olavs Hospital and Active Against Cancer — Gjensidige Foundation supported this study. Thune reports no relevant financial disclosures. Pease see the abstract for all other authors’ relevant financial disclosures.