Oxidative stress alterations following an exercise intervention in cancer survivors

Exercise interventions in cancer patients have been demonstrated to reduce cancer-treatment related side effects. Despite this, the underlying mechanisms associated with the protective aspects of exercise are generally uncharacterized, but treatment-associated oxidative stress is thought to play a role. The purpose of this study was to determine the effect of an exercise intervention on fatigue, cardiorespiratory fitness (CRF), muscular strength, and blood markers of DNA and protein oxidation compared to a non-exercising, cancer control group. METHODOLOGY: An initial fasting blood draw and assessments of muscular strength and CRF were administered to fifteen cancer patients within six weeks of completing radiation or chemotherapy treatment. Eight cancer patients participated in a 10-week exercise intervention (EX) while seven continued standard care (CON). Following the intervention, subjects completed another fasted blood draw and a reassessment of fatigue, strength and CRF. Changes in plasma protein carbonyls, 8-OHdG, and antioxidant status were compared between the exercise and control groups. Baseline markers of oxidative stress were compared between healthy individuals (NC) and cancer patients. A correlation analysis of changes in fitness parameters and oxidative stress in cancer patients was conducted. RESULTS: Baseline total antioxidant capacity was significantly lower, and plasma protein carbonyls significantly higher in cancer patients compared to NC (p \u3c 0.05). Mean total fatigue scores decreased significantly from 5.0 ± 2.2 to 2.6 ± 1.5 (p \u3c 0.05) in EX, whereas changes in CON (4.7 ± 2.5 to 3.2 ± 2.4) were not significant. All fatigue subscales significantly decreased in EX, while only cognitive fatigue increased significantly in CON (p \u3c 0.05). Antioxidant capacity increased and protein carbonyls decreased in EX (p \u3c 0.01) but not CON. Improvements in composite arm (41%) and leg strength (34%), isometric handgrip strength (11%), and VO2peak (16%) all significantly improved in the EX group (p \u3c 0.05), while none of these parameters significantly changed in CON. No significant changes over time were found in 8-OHdG, but a group by time interaction effect was detected (p \u3c 0.05). Baseline antioxidant capacity significantly correlated (p \u3c 0.05) with total, affective, sensory, and cognitive fatigue. Increases in antioxidant capacity were correlated (p \u3c 0.05) with reductions in affective, sensory, and cognitive fatigue. Although 8-OHdG was not correlated with any fatigue parameter at baseline, changes in total and affective fatigue exhibited significant correlations with changes in 8-OHdG over time. CONCLUSIONS: A whole-body exercise intervention is an effective method of increasing muscular strength, CRF and antioxidant capacity, while reducing markers of protein oxidation. An exercise intervention was an effective method of reducing fatigue in cancer patients following cessation of treatment, whereas standard care resulted in non-significant reductions in fatigue. Oxidative stress may be implicated in cancer-related fatigue, while improved antioxidant capacity following an exercise intervention may play a role in mitigating fatigue