PON1 and neutropenia: In this study, we aimed to evaluate the oxidant (MDA) and antioxidant (PON1 and ARE) parameters in patients with neutropenia secondary to chemotherapy in the neutropenic period (ANC< 1000/mm3) and after the elimination of neutropenia with use of filgrastim (leukocyte count> 10,000/mm3), in order to understand the oxidative stress status in these conditions.