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

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. Exercise 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 performed 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 unaltered, 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 cytotoxicity, 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 influence 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 responsive to exercise. Next, differential effects of training types and intensities on these markers should be further investigated, as well as their clinical implications.