Erhola M, Nieminen M M, Ojala A, Metsä-Ketelä T, Kellokumpu-Lehtinen P, Alho H
Tampere University Medical School Department of Respiratory Medicine, Tampere, Finland.
J Exp Clin Cancer Res. 1998 Sep;17(3):325-30.
Even though it is well established that oxygen-free radicals are the main mechanism responsible for the cytotoxicity produced during radiotherapy, the role of the human antioxidant defense system in clinical radiation oncology is still to be clarified. Changes in the human plasma total peroxyl radical trapping capacity (TRAP) and its individual components were followed during clinical radiotherapy for lung cancer. Sixteen patients receiving radical-aimed radiotherapy provided blood samples nine times during the treatment. Our hypothesis was that oxygen-free radical production increased by irradiation should decrease the plasma TRAP as a consequence of oxidative stress. Only a moderate reduction of the plasma TRAP was found during the therapy in the study group taken as a whole, but the development pattern of TRAP and its unidentified components were clearly different in those patients showing complete or partial response to the treatment and those in which the disease progressed unabated. Plasma ascorbate levels showed no significant changes during radiotherapy. A decrease in vitamin E concentrations was seen after 6 Gy (p=0.05). Uric acid concentrations increased towards the end of the radiotherapy in both response groups (p=0.02 at 50 Gy). In this study, 26.6% of the plasma TRAP was due to unidentified antioxidants (UNID).
尽管已有充分证据表明，氧自由基是放疗过程中产生细胞毒性的主要机制，但人体抗氧化防御系统在临床放射肿瘤学中的作用仍有待阐明。在肺癌临床放疗期间，对人体血浆总过氧自由基捕获能力（TRAP）及其各个组分的变化进行了跟踪研究。16例接受根治性放疗的患者在治疗期间提供了9次血样。我们的假设是，辐射导致的氧自由基生成增加，会因氧化应激而使血浆TRAP降低。在整个研究组的治疗过程中，仅发现血浆TRAP有适度降低，但在对治疗显示出完全或部分反应的患者与疾病持续进展的患者中，TRAP及其未明确组分的变化模式明显不同。放疗期间血浆抗坏血酸水平无显著变化。照射6 Gy后维生素E浓度降低（p = 0.05）。两个反应组在放疗接近尾声时尿酸浓度均升高（50 Gy时p = 0.02）。在本研究中，26.6%的血浆TRAP归因于未明确的抗氧化剂（UNID）。
