Assessment of Plasma Antioxidants, Oxidative Stress and Polyunsaturated Fatty Acids in Paediatric Cancer Patients: A Prospective Cohort Pilot Study

Background: Paediatric cancer patients may have a limited dietary intake, particularly nutrients high in antioxidants, docosahexanoic acid (DHA) and eicosapentanoic acid (EPA). Objective: To investigate the antioxidant status (TAS), antioxidant capacity (TAC), oxidative stress, DHA and EPA of paediatric cancer patients during treatment. Methods: A prospective cohort study of Scottish children aged <18 years, diagnosed with and treated for cancer between April-2013 to Jan-2014 was performed. Clinical data and blood samples were collected at baseline and 6 months. Data were stratified by treatment risk (low, medium and high) and nutritional support. We used Oxygen Radical Absorbance Capacity (ORAC) Antioxidant Assay to measure TAC, thiobarbituric acid reactive substances (TBARS) for lipid peroxidation and high performance liquid chromatography and Inductively Coupled Plasma Mass Spectrometry for TAS. The analyses of DHA and EPA were performed by analysing fatty acidmethyl esters (FAME) using gas-liquid chromatography. The reference ranges used were: Yagi 1998 (1.86-3.94) μmol for lipid peroxidation and Damsgaard.,et al. 2014 for EPA (0.45-0.77) % and DHA (2.22-3.76) %. Results: 20 patients (median (IQR) age 4.2 (1.5-8.5) years; 50% males) were recruited. There were no significant changes in plasma TAS, TAC and EPA, but lipid peroxidation significantly decreased from 7.4 (6.2-9.0) at baseline to 5.3 (4.5-6.4) μmol/MDA at 6 months(p = 0.003). The median (IQR) blood percentage of DHA significantly increased from 1.3 (0.9-1.9) to 1.8 (1.3-2.1) (p = 0.001). Lipid peroxidation was high in 95% (19/20) of patients at baseline and 94% (15/16) at 6 months; whilst DHA and EPA were low in 95%(19/20) and 70% (14/20) at baseline and 87.5% (14/16) and 60% (12/16) at 6 months. Children on high-treatment risk exhibited the highest oxidative stress levels. No statitically significant differences were found between non-supplemented and supplemented children in any of the following parameters (TAS, TAC, oxidative stress, EPA and DHA). Conclusion: There was a high prevalence of oxidative stress, especially in children treated with high-risk protocols and during the initial phases of treatment. Nutritional support does not appear to provide enough TAS, EPA and DHA in this cohort; however, larger high-quality population based studies are warranted to confirm these findings. Keywords: Paediatric cancer; Antioxidants; Oxidative stress; Docosahexanoic acid; Eicosapentanoic acid