Exercise Interventions in Breast Cancer: Molecular Mechanisms, Physical Benefits, and Practical Recommendations

Exercise interventions are increasingly recognized as effective non-pharmacological strategies to improve clinical outcomes in patients with breast cancer. This review provides a comprehensive framework linking physical activity with breast cancer risk reduction, disease progression, and survivorship. We first outline the robust epidemiological evidence demonstrating that regular exercise significantly reduces breast cancer incidence, recurrence, and disease-specific mortality. The review then delves into the molecular mechanisms by which exercise exerts its protective effects, including modulation of sex hormones, metabolic hormones, systemic inflammation, oxidative stress, circulating microRNAs, and breast cancer-related DNA methylation. Furthermore, we summarize findings from clinical trials evaluating the effects of exercise on cardiorespiratory fitness, functional capacity, and quality of life in breast cancer patients. Emerging research on the synergistic potential of exercise with conventional cancer treatments and bioactive dietary components, particularly polyphenols such as saffron and curcumin, is also discussed. Finally, we present evidence-based exercise recommendations tailored to breast cancer patients, emphasizing the importance of individualized prescriptions to optimize safety and therapeutic benefit. Collectively, this review highlights the multifaceted role of exercise in breast cancer prevention, treatment, and survivorship.