Physical activity (PA) following surgery for breast cancer may improve depressive symptoms and quality of life (QoL) via reduction in fatigue-related daily interference (FRDI). Less is known about how change in PA may relate to these psychosocial factors throughout the course of treatment. In a secondary analysis of a previous psychosocial intervention trial, we examined relationships between change in PA, depressive symptoms, and functional QoL, as mediated by change in FRDI, and whether naturally occurring change in PA provided benefit independent of the intervention.

Women (N=240) with non-metastatic stage 0–III breast cancer were randomized to cognitive-behavioral stress management (CBSM) or a control 2–10weeks post-surgery. PA, FRDI, clinician-rated depressive symptoms, self-reported depressed mood, and functional QoL were assessed at baseline and three months post-intervention.

Increased PA was associated with reductions in clinician-rated depressive symptoms, depressed mood, and improved QoL, mediated by a reduction in FRDI. This was above and beyond the effect of CBSM.

Increased PA may mitigate FRDI and improve depressive symptoms and functional QoL for women undergoing breast cancer treatment, beyond effects of a psychosocial intervention. Benefits of an integrated PA and psychosocial approach should be investigated further.