Last update:
31-Mar-2011

OBJECTIVE Chemotherapy results of increase in free radical formation and depletion of tissue antioxidants. It has also been claimed that antioxidants can increase the effectiveness of cytotoxic therapy and their use during chemotherapy has been recommended, although some clinicians advise their patients against the use of antioxidant dietary supplements during chemotherapy, suggesting that they could be harmful the therapy. The aims of this study were to determine the antioxidant status of patients during chemotherapy and its correlation with sex and with frequency of administration of the chemotherapy.

METHOD Serum trolox equivalent antioxidant capacity (TAC) was measured in 51 patients (16 male and 35 female) during chemotherapy. 17 patients were receiving their therapy once a week and 34 daily. Antioxidant activity was estimated by the effect of serum on the oxidation of 2.2'-azino-bis(3-ethylbenthiazoline)-6-sulfonic acid by the ferryl myoglobin-H₂O₂ system. Trolox, the water soluble analogue of vitamin E, was used as the control. The antioxidant concentration was expressed as trolox equivalents.

RESULTS-CONCLUSIONS A significant decrease in serum TAC was observed in all the patients during chemotherapy (by a mean of 67.3% decrease compared to normal levels, p=0.001). There was also a differentiation in serum TAC related to both sex and the frequency of chemotherapy: Lower serum TAC levels were detected in male patients, and in patients receiving chemotherapeutic drugs daily, compared to those receiving chemotherapy once a week.

Key words: Chemotherapy, Oxidative stress, Sex, TAC.