Moderators of the effects of exercise training in breast cancer patients receiving chemotherapy: a randomized controlled trial.
BACKGROUND
Exercise training improves supportive care outcomes in patients with breast cancer who are receiving adjuvant therapy, but the responses are heterogeneous. In this study, the authors examined personal and clinical factors that may predict exercise training responses.


METHODS
Breast cancer patients who were initiating adjuvant chemotherapy (N=242) were assigned randomly to receive usual care (UC) (n=82), resistance exercise training (RET) (n=82), or aerobic exercise training (AET) (n=78) for the duration of chemotherapy. Endpoints were quality of life (QoL), aerobic fitness, muscular strength, lean body mass, and body fat. Moderators were patient preference for group assignment, marital status, age, disease stage, and chemotherapy regimen.


RESULTS
Adjusted linear mixed-model analyses demonstrated that patient preference moderated QoL response (P= .005). Patients who preferred RET improved QoL when they were assigned to receive RET compared with UC (mean difference, 16.5; 95% confidence interval [95% CI], 4.3-28.7; P= .008) or AET (mean difference, 11; 95% CI, -1.1-23.4; P= .076). Patients who had no preference had improved QoL when they were assigned to receive AET compared with RET (mean difference, 23; 95% CI, 4.9-41; P= .014). Marital status also moderated QoL response (P= .026), age moderated aerobic fitness response (P= .029), chemotherapy regimen moderated strength gain (P= .009), and disease stage moderated both lean body mass gain (P< .001) and fat loss (P= .059). Unmarried, younger patients who were receiving nontaxane-based therapies and had more advanced disease stage experienced better outcomes. The findings were not explained by differences in adherence.


CONCLUSIONS
Patient preference, demographic variables, and medical variables moderated the effects of exercise training in breast cancer patients who were receiving chemotherapy. If replicated, these results may inform clinical practice.
Courneya
Kerry S
KS
Faculty of Physical Education and Recreation, University of Alberta, Edmonton, Alberta, Canada. kerry.courneya@ualberta.ca
McKenzie
Donald C
DC
Mackey
John R
JR
Gelmon
Karen
K
Reid
Robert D
RD
Friedenreich
Christine M
CM
Ladha
Aliya B
AB
Proulx
Caroline
C
Vallance
Jeffrey K
JK
Lane
Kirstin
K
Yasui
Yutaka
Y
Segal
Roanne J
RJ
D000273:Adipose Tissue / Q000473:pathology; D000367:Age Factors; D000971:Antineoplastic Combined Chemotherapy Protocols / Q000627:therapeutic use; D001294:Attitude to Health; D001823:Body Composition; D001943:Breast Neoplasms / Q000188:drug therapy* / Q000628:therapy; D017024:Chemotherapy, Adjuvant; D005081:Exercise Therapy / Q000145:classification / Q000379:methods*; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D017533:Marital Status; D008875:Middle Aged; D053580:Muscle Strength / Q000502:physiology; D018482:Muscle, Skeletal / Q000473:pathology; D009367:Neoplasm Staging; D010101:Oxygen Consumption / Q000502:physiology; D010809:Physical Fitness / Q000502:physiology; D011788:Quality of Life; D016896:Treatment Outcome