Effects of Exercise during Chemo- or Radiotherapy on Immune Markers: A Systematic Review

Abstract

Introduction: Patients with cancer receiving radio- or chemotherapy undergo many immunological stressors. Chronic regular exercise has been shown to positively influence the immune system in several populations, while exercise overload may have negative effects. Ex- ercise is currently recommended for all patients with cancer. However, knowledge regarding the effects of exercise on immune markers in patients undergoing chemo- or radiotherapy is limited. The aim of this study is to systematically review the effects of moderate- and high-intensity exercise interventions in patients with cancer during chemotherapy or radiotherapy on immune markers. Methods: For this review, a search was per- formed in PubMed and EMBASE, until March 2023. Methodological quality was assessed with the PEDro tool and best-evidence syntheses were performed both per immune marker and for the inflammatory profile. Results: Methodological quality of the 15 included articles was rated fair to good. The majority of markers were unal- tered, but observed effects included a suppressive effect of exercise during radiotherapy on some pro- inflammatory markers, a preserving effect of exercise during chemotherapy on NK cell degranulation and cy- totoxicity, a protective effect on the decrease in thrombocytes during chemotherapy, and a positive effect of exercise during chemotherapy on IgA. Conclusion: Although exercise only influenced a few markers, the results are promising. Exercise did not negatively influ- ence immune markers, and some were positively affected since suppressed inflammation might have positive clinical implications. For future research, consensus is needed regarding a set of markers that are most re- sponsive to exercise. Next, differential effects of training types and intensities on these markers should be further investigated, as well as their clinical implications.