Exercise-induced immune response in breast cancer patients during prehabilitation, neoadjuvant or adjuvant treatment: A systematic review and meta-analysis.

[BACKGROUND] Adjuvant and neoadjuvant treatment for breast cancer (BC) such as chemotherapy and radiotherapy can lead to immune system impairment. Exercise is hypothesized to mitigate these effects by modulating immune responses and reducing chronic inflammation. This review aims to summarize the existing evidence on the impact of physical exercise on inflammatory markers and cellular immune function in patients with BC during prehabilitation, adjuvant or neoadjuvant treatment.

[METHODS] A systematic literature search was conducted in PubMed, Web of Science, Scopus and Embase to identify randomized controlled trials investigating exercise interventions in individuals with BC undergoing medical treatment. The included studies assessed outcomes on markers of immune function and inflammation. Subgroup analyses were undertaken for type of training, supervision, risk of bias, timing, duration and intensity of intervention and sample size.

[RESULTS] Twenty randomized controlled trials, including 1109 participants, were included in this review. Based on the available evidence, no significant influence of exercise on the determined immune factors and markers of inflammation could be confirmed.

[CONCLUSIONS] These meta-analyses suggest that exercise does not significantly alter immune function or markers of inflammation in BC patients during prehabilitation, adjuvant or neoadjuvant treatment. As no negative effect was observed, exercise appears to be safe and should be recommended to patients during cancer treatment because of its beneficial effects on quality of life, fatigue, cancer-related pain and survival.