In a Canadian study reported in the Journal of the National Cancer Institute, Kerry S. Courneya, PhD, of the University of Alberta, and colleagues assessed the impact of different levels of physical exercise on physical functioning in women receiving adjuvant chemotherapy for breast cancer. They found that higher volumes of aerobic or combined exercise may reduce declines in physical functioning better than standard volumes of aerobic exercise.
In this multicenter trial, 301 breast cancer patients were randomly assigned during chemotherapy to thrice-weekly supervised exercise consisting of 25 to 30 minutes of aerobic exercise (standard dose; n = 96), 50 to 60 minutes of aerobic exercise (high dose; n = 101), or a combination of 50 to 60 minutes of aerobic and resistance exercise (combination; n = 104). Participants exercised for the duration of chemotherapy beginning 1 to 2 weeks before and ending 3 to 4 weeks after chemotherapy.
The primary endpoint was physical functioning assessed by the Medical Outcomes Survey-Short Form (SF)-36. Secondary physical health measures were the SF-36 components role-physical, bodily pain, general health, and physical component summary score and the Functional Assessment of Cancer Therapy (FACT) trial outcome index-fatigue score. Secondary symptom measures included FACT scales for breast cancer, fatigue, taxane/neuropathy, and endocrine symptoms, health-related fitness measures, and chemotherapy completion rates.
Overall, patients had a mean age of 50 years and 85% were white; 17% of the standard-dose group, 16% of the high-dose group, and 36.5% of the combination group were obese; 31%, 29%, and 31% were aerobic exercisers; 74% of each group was receiving no trastuzumab/any taxane; and 50%, 57%, and 61.5% were receiving a breast-conserving surgery protocol.
Follow-up assessment of patient-reported outcomes was 99.0%. Planned chemotherapy regimens ranged from 12 to 26 weeks (mean, 16.3 weeks), and the mean duration of the exercise intervention was 16.4 weeks. The standard-dose, high-dose, and combination groups completed 88%, 82%, and 78% of prescribed aerobic sessions, respectively (P = .004). The average duration of aerobic sessions was 28, 48, and 27 minutes, respectively, and the average weekly durations were 73, 120, and 64 minutes, respectively (P < .001). Average intensity of aerobic exercise was 68%, 65%, and 67% of VO2 peak (P = .005). The combination group attended 66% of their resistance exercise sessions and completed ≥ 98% of prescribed weight, sets, and repetitions in each session.
Physical Health Measures
There were no significant adjusted between-group differences in the primary endpoint of SF-36 physical functioning for the combination vs standard-dose group (mean difference, +0.5, P = .52), high-dose vs standard-dose group (+0.8, P = .30), or high-dose vs combination group (+0.3, P = .70).
With regard to secondary physical health measures, there were no significant differences between the combination vs standard-dose group. Significant improvements for the high-dose vs standard-dose group were observed for bodily pain (+2.3, P = .02) and physical component summary score (+1.6, P = .04) and a borderline significant improvement was observed in trial outcome index-fatigue (+3.3, P = .09). There was a significant improvement for the high-dose vs combination group in bodily pain (+2.0, P = .04) and a borderline significant improvement in physical component summary score (+1.2, P = .10).
For symptoms, both the high-dose (+2.2, P = .02) and combination groups (+2.5, P = .009) had significant improvement vs the standard-dose group in endocrine symptoms and the high-dose group had a borderline significant improvement vs the standard-dose group in fatigue (+1.8, P = .10).
Health-Related Fitness and Chemotherapy Completion Rate
The combination group had significantly better upper body muscular strength (P = .001 for both) and endurance (P = .001 for both) and lower body muscular strength (P = .01 for both) vs both the standard-dose and high-dose groups, as well as significantly better lower body muscular endurance vs the high-dose group (P = .006) and borderline better lower body muscular endurance vs the standard-dose group (P=.06). The standard-dose group had significantly better upper body strength vs the high-dose group (P = .02). For VO2peak, the high-dose group had significantly greater improvement vs the combination group (P = .03) and borderline greater improvement vs the standard-dose group (P = .08). No differences among groups were observed for body weight, lean mass, fat mass, or body fat.
Relative chemotherapy dose intensities were 94%, 92%, and 93%, in the standard-dose, high-dose, and combination groups, respectively (P = .34), and the proportions of patients receiving ≥ 85% planned relative dose intensity were 87.5%, 82%, and 86%, respectively (P = .57).
The investigators concluded, “A higher volume of aerobic or combined exercise is achievable and safe during breast cancer chemotherapy and may manage declines in physical functioning and worsening symptoms better than standard volumes.”
This study was funded by the Canadian Breast Cancer Research Alliance.
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