Oxidative stress has a potential role in carcinogenesis. Antioxidant enzymes have neutralizing effect both on cancer initiation, and progression. We aimed to assess the oxidant and antioxidant levels of pediatric cancer patients and to compare the levels in healthy controls.

The study involved 105 pediatric cancer patients (40 undergoing chemotherapy, 65 survivors) and 40 healthy children. The serum total oxidant status (TOS) and total antioxidant status (TAS) were measured.

The TOS and oxidative stress index were lower in pediatric cancer patients compared to the levels in the controls (3.73±1.35 vs. 4.21±1.72 µmol/L; p=0.08; 0.20±0.07 vs. 0.26±0.10; p=0.001, respectively). The mean serum TAS level was higher in patient groups compared to the level in the control (1.87±0.48 vs. 1.63±0.32 mmol/L, p=0.001). The TAS level of children with cancer in survivors was still found to be significantly higher compared to the levels in the control group (1.85±0.45 vs. 1.63±0.32 mmol/L, p=0.005). Radiotherapy, surgery, relapsed disease, presence of metastases and receiving enteral nutritional support caused no change in the TAS/TOS level.

It has been revealed for the first time that the serum total antioxidant level increased during cancer treatment and didn't normalize after cessation of therapy for a long time.