Purpose: Deleterious effects of ionizing radiation and some chemotherapeutic agents are predominantly caused by reactive oxygen agents which are detoxified by antioxidants. This study was designed to evaluate the modifying effects of vitamin A-, vitamin E- and selenium serum concentrations and glutathione peroxidase activity on preoperative radio- and chemotherapy of breast cancer.
Patients and methods: Tumor volume, vitamin A-, vitamin E-, selenium serum concentrations and glutathione peroxidase activity in circulating erythrocytes were determined in 40 patients with breast cancer before treatment. Interstitial radiohyperthermia was given initially using a single dose of 10 Gy (HDR) combined with hyperthermia between 43.5 to 44.5 degrees C over 60 minutes followed by external beam radiotherapy with 50 Gy in 5 weeks. All patients received anthracyline or anthrachinone containing chemotherapy. Tumor response was determined by histopathological examination. Patients with complete and incomplete remissions were compared using the Wilcoxon test. Pre- and posttreatment tumor-volume differences were correlated with antioxidant concentrations (Spearman correlation coefficient).
Results: Twenty patients (50%) achieved a complete histopathologic tumor regression. This high complete remission rate was not related to the antioxidants under investigation (vitamin A: p = 0.32, vitamin E: p = 0.44, selenium: p = 0.68, glutathione peroxidase: p = 0.3). There was no correlation to pre- and posttreatment tumor-volume-differences either (vitamin A: p = 0.89, vitamin E: p = 0.67, selenium: p = 0.41, glutathione peroxidase: p = 0.87).
Conclusions: In this study serum concentrations of antioxidants had no modifying influence on tumor response in breast cancer patients following induction radio-chemotherapy and subsequent surgery. Further studies measuring tissue levels could clarify if there is any modifying influence of antioxidants on tumor remission.