Benefits of Physical Activity on Depression and Functional Quality of Life During Treatment for Breast Cancer: Psychosocial Mechanisms.

Women who are post surgery for breast cancer (BCa) experience distressing side effects that negatively influence Quality of Life (QoL). Physical activity (PA) following a BCa diagnosis is associated with decreased mortality, reduced recurrence, increased functional capacity, less fatigue, and may improve depression and QoL. Furthermore, evidence suggests that a combined PA and psychotherapy intervention may reduce physically and emotionally distressing side effects associated with diagnosis and treatment. The purpose of the study is to examine relationships among PA, fatigue, clinician-rated depression, depressed mood, and QoL in women after undergoing surgery for BCa and to assess the continuity of these relationships as they move through adjuvant treatment. In addition, the study investigates whether fatigue is an underlying psychosocial mechanism accounting for the effects of PA on study outcomes. Finally, given prior evidence that participation in a Cognitive-Behavioral Stress Management (CBSM) intervention was associated with reduced fatigue, the study assesses whether women who were physically active showed less fatigue above and beyond the effects of CBSM. Women (N=240) with non-metastatic stage 0-III BCa were recruited 2-10 weeks post-surgery and randomized to either a CBSM intervention group or a psycho-educational control group. Physical activity, fatigue, functional QoL, rated depression, and depressed mood were assessed at the baseline and 3-month post intervention time points. Structural equation modeling was used to test hypotheses. At baseline, results revealed that greater PA was associated with less fatigue-related daily interference (FRDI), and that less FRDI was associated with greater functional QoL, lower rated depression, and less depressed mood. Furthermore, lower FRDI was a pathway by which greater PA was associated with greater functional QoL, less rated depression, and less depressed mood. These relationships were similar at the 3-month post intervention time point and when difference scores were used in the model. Finally, PA contributed significantly to the change in FRDI above and beyond the effects of participation in CBSM. A combined PA and CBSM intervention may be effective in reducing FRDI, and improving depressive symptoms and QoL for women after surgery for BCa and during adjuvant treatment, and should be investigated in future studies