קרינה

האונקולוג מבקש להפסיק אנטיאוקסידנטים בזמן קרינה ???

מהמחקרים הקליניים הקטנים והוריאבילים שפורסמו עד כה יש ממצאים ודעות לכאן ולכאן. חלקם אומרים זה עוזר, חלקם אומרים לא עוזר, חלקם אומרים זה אפילו מזיק. מאמר סקירה מ 2008 http://jnci.oxfordjournals.org/content/100/11/773 מאמר סקירה מדצמבר 2011 http://informahealthcare.com/doi/full/10.3109/07357907.2011.626479 Cancer Invest. 2011 Dec;29(10):655-67. Systematic review: generating evidence-based guidelines on the concurrent use of dietary antioxidants and chemotherapy or radiotherapy. Nakayama A, Alladin KP, Igbokwe O, White JD. Source Preferred Staffing Group, Inc., Washington, District of Columbia, USA. Abstract The risk-benefit ratio for concurrent use of dietary antioxidants with chemotherapy or radiation therapy is a controversial topic. In this review, the medical literature on concurrent antioxidant use with chemotherapy or radiotherapy was assessed and further steps for generating evidence-based guidelines are suggested. The clinical cancer research community should cooperate and focus new studies on the use of a specific combination of antioxidant and chemotherapy or radiotherapy, and determine optimal doses for a specific cancer setting. Mechanistic studies on the interaction between antioxidants and conventional cancer therapy could lead to novel biomarkers for assessing dose adequacy קטעים מהמאמר Recent studies show that an increasing number of Americans are seeking complementary and alternative medicine (CAM) (1, 2). Cancer patients are among those who are looking to CAM for more treatment options to improve their disease status as well as their quality of life. Many cancer patients use dietary supplements with antioxidants during or after conventional cancer treatment attempting to enhance the benefits of treatment, prevent or palliate side effects, or maintain or improve general health and well-being (3–5). Cancer patients continue to do this regardless of a relative lack of high-level evidence of antioxidant's safety, efficacy, or benefit when combined with conventional cancer therapies. There are conflicting arguments regarding the use of antioxidant supplements while a cancer patient is undergoing conventional treatment. One position is that antioxidants help protect and repair healthy cells that are damaged by chemotherapy or radiation therapy, which can result in fewer or less severe side effects. Proponents of this argument also assert the ability of antioxidants to directly induce apoptosis in malignant cells and to enhance antitumor effects of chemotherapy in vitro and in vivo (7–10). Opponents are concerned that antioxidants directly oppose the mechanisms of conventional cancer treatment, working to repair and protect cells by lowering oxidative damage, while many cancer treatments aim to destroy cancer cells by causing oxidative damage (11, 12). Many published studies have reported the effects of antioxidants as an adjuvant therapy for cancer patients while undergoing conventional cancer therapy. Recent reviews have come to divergent opinions about the appropriateness of recommendations to patients for (9, 10) or against (13, 14) the concurrent use of antioxidants with either chemotherapy or radiation therapy. Although questions about the risk–benefit ratio have apparently been adequately answered for some, intriguing results from various studies have prompted many to call for more research (13, 15–18). Fifty-two clinical trials, which investigated the concurrent use of diet-derived antioxidants with chemotherapy and/or radiotherapy, were found. Among them, 26 clinical trials used glutathione or reduced glutathione (GSH) (22–47), 11 used a type of vitamin E such as α-tocopherol or dl-α-tocopherol acetate (48–59), 5 used N-acetylcysteine (NAC; 60–64), and others (n = 10) used vitamin C, selenium, coenzyme Q10, zinc, or a combination of antioxidants (65–74; Table 1). The ability of physicians and patients to make confident assessments of the risk–benefit ratio of concomitant use of dietary antioxidants with conventional cancer therapies is limited by many factors including the presence of significant gaps in clinical trial results. Clinical trials examining the potential benefit of these combinations have been conducted since the late 1980s. However, despite many trials demonstrating positive effects of combined therapies, none of the combinations has yet gained widespread acceptance in clinical practice. Many of these trials were small and thus lack sufficient statistical power to provide robust answers. Meta-analyses have not been done and would be unlikely to provide more clarity for the reasons stated below. CONCLUSION Clinical research exploring combinations of dietary antioxidants and chemotherapy or radiation therapy has seemingly focused on the demonstration of a detectable advantage, or disadvantage, over chemotherapy, or radiation therapy alone. Several published studies have provided individual results addressing these questions, but the resulting portfolio of findings is inadequate to allow the confident development of specific clinical guidelines of appropriate use either for the mitigation of therapy-related side effects or the augmentation of anticancer activity. A greater homogeneity of treatment protocols in the future and more thorough reporting of the antioxidant type and formulation used would produce results that could be used to determine if evidence-based recommendations for or against the use of specific combinations in specific clinical situations are warranted.