Effects of exercise on inflammation in female survivors of nonmetastatic breast cancer: a systematic review and meta-analysis

Background: Despite advances in breast cancer treatment, recurrence remains common and contributes to higher mortality risk. Among the potential mechanisms, inflammation plays a key role in recurrence by promoting tumor progression. Exercise provides a wide array of health benefits and may reduce inflammation, potentially reducing mortality risk. However, the effects of exercise, including mode (ie, resistance training [RT], aerobic training [AT], and combined RT and AT) and program duration, on inflammatory biomarkers in breast cancer survivors remain to be elucidated. Methods: A systematic search was undertaken in PubMed, CINAHL, Embase, SPORTDiscus and CENTRAL in August 2024. Randomized controlled trials examining the effects of exercise on IL-1β, IL-6, IL-8, IL-10, TNF-α, and CRP were included. A random-effects meta-analysis was undertaken to quantify the magnitude of change. Results: Twenty-two studies were included (n = 968). Exercise induced small to large significant reductions in IL-6 (SMD = -0.85; 95% CI = -1.68 to -0.02; p = .05) and TNF-α (SMD = -0.40; 95% CI = -0.81 to 0.01; p = .05) and a trend for a decrease in CRP. When stratifying by exercise mode, trends toward reduction in IL-6 and TNF-α were observed for combined exercise, whilst changes were not generally affected by exercise program duration. Conclusion: Exercise, especially combined RT and AT, can reduce pro-inflammatory biomarkers, and may be a suitable strategy to reduce inflammation in breast cancer survivors. However, further research is needed to investigate the effects of exercise mode and program duration on markers of inflammation in this survivor group.