Abstract

Ionizing radiation as a treatment for breast cancer is based on damaging DNA and producing free radicals in neoplastic cells to induce apoptosis or necrosis. The effects of radiotherapy (RT) are systemic due to a lack of specificity and damage to non- neoplastic cells, provoking oxidative stress in the organism. In this work, we studied 25 patients with breast cancer between 26 and 75 years of age who received RT after surgery and chemotherapy to study the presence of oxidative, inflammatory, and metabolic stresses to characterize the disease, the effects of treatment, and the body's response. The work measured the molecular indicators before RT, at the beginning of it, and at the end of all RT sessions. We found metabolic stress characterized by the mobilization of ketone bodies evaluated by a high concentration of ß-hydroxybutyrate; oxidative stress identified by a high degree of oxidation assessed by lipoperoxidation and low antioxidant response assessed by total antioxidant capacity and catalase activity; as well as proinflammatory stress indicated by a high concentration of IL-6. These conditions were associated with increased erythrocyte and leukocyte apoptosis and increased leukocyte necrosis. Our results indicate that ionizing radiation induced or exacerbated the three types of stress; while these effects concur with the purposes of the treatment on cancer cells, other cells of the organism are affected in the same way. We also propose a predictive equation that uses clinical-molecular parameters for the breast cancer prognosis.

Key Words: Brest cancer; oxidative stress; ionizing radiation; metabolic stress; proinflammatory stress;