Effects of an Exercise Intervention on Cancer-Related Fatigue and Its Relationship to Markers of Oxidative Stress

Background: Although the underlying mechanisms of cancer-related fatigue (CRF) are not fully characterized, treatment-associated oxidative stress may play a role. The purpose of this study was to determine the effect of an exercise intervention on the relationship between CRF and oxidative stress. Methods: Upon cessation of radiation or chemotherapy, 8 cancer patients participated in a 10-week exercise intervention (EX), while 7 continued standard care (CON). Blood draws and fatigue questionnaires were administered to cancer patients before and after the intervention as well as to 7 age-matched individuals with no cancer history. Changes in plasma 8-hydroxy-deoxyguanosine (8-OHdG), protein carbonyls, antioxidant capacity, and fatigue were compared between groups. Correlations between CRF and oxidative stress were evaluated. Results: Mean total fatigue scores decreased significantly (5.0 +/- 2.2 to 2.6 +/- 1.5, P < .05) in EX, but not in CON. Antioxidant capacity significantly increased (+41%; P < .05) and protein carbonyls significantly decreased (-36%; P < .05) in EX, but not in CON. Increases in antioxidant capacity were significantly correlated with reductions in affective (r = -.49), sensory (r = -.47), and cognitive fatigue (r = -.58). Changes in total (r = .46) and affective (r = .47) fatigue exhibited significant correlations with changes in 8-OHdG over time, while behavioral (r = .46) and sensory (r = .47) fatigue changes were significantly correlated with protein carbonyls. Conclusions: Oxidative stress may be implicated in CRF, while improved antioxidant capacity following an exercise intervention may play a role in mitigating CRF in cancer survivors.