The effects of exercise on cancer-related fatigue in breast cancer patients during primary treatment: a meta-analysis and systematic review.

INTRODUCTION: Cancer-related fatigue is one of the most prevalent symptoms reported by breast cancer survivors. Despite a corpus of literature dedicated to understanding and identifying evidence-based treatments for cancer-related fatigue, gaps in the literature remain, particularly for breast cancer survivors during their primary treatment. Exercise training may represent an efficacious behavioral modality for mitigating fatigue symptoms in cancer survivors; yet, the effects of exercise during adjuvant therapy is an understudied area. AREAS COVERED: In this review, we synthesize the most recent evidence of exercise's effects on cancer-related fatigue during active treatment for breast cancer. We summarize the overall effects of exercise, moderators of these effects, and areas requiring further research. EXPERT OPINION: Strong evidence supports at least modest effects of exercise on cancer-related fatigue during breast cancer treatment. However, several knowledge gaps persist, including the need to: risk stratify patients to tailor exercise promotion strategies; implement higher-quality studies and translate this evidence to clinical practice; adopt biobehavioral models to better understand exercise's effects on cancer-related fatigue; evaluate the effects of exercise modes besides aerobic and combined training; and integrate technology to better understand and promote fatigue-reducing behaviors, such as exercise, across cancer care.