תוספי מזון, כימותרפיה ורדיותרפיה

עדיין לא הוכח קלינית שנוגדי חימצון משפיעים באופן משמעותי על הפרוגנוזה של חולי סרטן המטופלים בכימותרפיה או רדיותרפיה. יתכן אפילו שבמקרים מסויימים הם לא רצויים. הם כן מפחיתים תופעות לוואי של הטיפולים. .CA Cancer J Clin. 2005 Sep-Oct;55(5):319-21 Use of antioxidants during chemotherapy AND radiotherapy should be avoided. Many patients being treated for cancer use dietary supplements, particularly antioxidants, in the hope of reducing the toxicity of chemotherapy AND radiotherapy. Some researchers have claimed, furthermore, that antioxidants also increase the effectiveness of cytotoxic therapy AND have explicitly recommended their use. However, mechanistic considerations suggest that antioxidants might reduce the effects of conventional cytotoxic therapies. Preclinical data are currently inconclusive AND a limited number of clinical studies have not found any benefit. Clinicians should advise their patients against the use of antioxidant dietary supplements during chemotherapy OR radiotherapy. Such caution should be seen as the standard approach for any unproven agent that may be harmful. Integr Cancer Ther. 2004 Dec;3(4):342-8 Antioxidants AND cancer therapy: furthering the debate. The consideration of whether to use antioxidants concomitantly with chemotherapy AND radiation therapy has evolved into a heated debate. This special theme issue brings together several contributors to this debate, whose perspectives enlarge our views of the questions at hand, pointing out several very relevant ideas. First, the early hypotheses of the role of antioxidants in carcinogenesis gave a simplified AND often inaccurate picture of the physiological effects of specific antioxidants. Antioxidants can have protective effects that have nothing to do with oxidation; on the other hand, they can under some circumstances develop prooxidant properties AND promote carcinogenesis. During treatment, however, their role is far from clear AND may be either quite positive OR potentially negative. A number of clinical studies have already demonstrated beneficial effects of antioxidants in ameliorating side effects of chemotherapy. More theoretical work on the chemistry of antioxidants AND chemotherapy drugs suggests that antioxidants might improve therapeutic efficacy of antineoplastics by counteracting aldehydes that impede the passage of cells through the cell cycle. However, detailed clinical study also makes it clear that we are only at the very beginning of understanding the dynamics of antioxidants AND oxidant damage in the body during conventional treatment. Nevertheless, research is under way on radioprotective AND chemoprotective substances, some of them rooted in traditional medicine AND others in our understanding of dietary antioxidants, that may eventually lead to antioxidant-based supplements that support tolerability AND efficacy of treatment, without protecting tumors through interference from antineoplastic treatm J Clin Oncol. 2004 Feb 1;22(3):517-28. Antioxidants AND cancer therapy: a systematic review. PURPOSE: Many patients with cancer take antioxidant nutritional supplements during cancer treatment to alleviate treatment toxicities AND to improve long-term outcomes, but little is known about the efficacy AND safety of antioxidant use during cancer treatment. We reviewed English-language manuscripts published in the biomedical literature, reporting the results of observational studies of antioxidant status AND cancer outcomes AND of intervention trials of antioxidants among patients receiving chemotherapy with OR without radiation for various malignancies. METHODS: We searched the Medline database AND the bibliographies of the retrieved manuscripts, reviews, AND books on antioxidants AND cancer. The retrieved studies are grouped by study design, malignancy, AND end points. RESULTS: More than 100 citations were retrieved; 52 met our criteria, 31 were observational studies, AND 21 were intervention trials. The studies varied in study design, timing of observation/intervention, intervention protocol, malignancy, AND anticancer regimen. CONCLUSION: These inconsistencies preclude a definitive conclusion as to the effect of chemotherapy on antioxidant status in patients undergoing anticancer therapy. However, our review suggests that total antioxidant status (measured by total radical antioxidant parameter) declines during cancer treatment. Adequately powered trials OR observational studies among patients with a specific cancer diagnosis receiving a specific treatment regimen are needed to address patients' AND physicians' concerns regarding these associations.