Chemotherapy :: Role of antioxidants in reducing chemotherapy toxicity

A new study showing a reduction in the toxic side effects of ROS-generating chemotherapies with concurrent antioxidant supplementation will be presented at the 43rd Annual Meeting of the American Society of Clinical Oncology (ASCO) that takes place June 1-5 at McCormick Place in Chicago.

According to the study?s authors, mitigating chemotherapy toxicity by supplementing with antioxidants may improve survival rates and tumor response by helping patients complete their prescribed treatment cycles.

?Antioxidants and toxicity of cancer chemotherapy: A systematic review of the evidence from randomized controlled trials? (Poster #PP1, Abstract #9130/36029) will be presented during the general poster session from 2-6 pm on Saturday June 2 in S Hall A2.

Lead author Keith I. Block, MD, co-founder and medical/scientific director of the Block Center for Integrative Cancer Treatment, will discuss the findings. The study was co-authored by Robert Newman, PhD, Professor of Cancer Medicine at M. D. Anderson Cancer Center.

The conclusions are based on a comprehensive review of the medical literature on the effects of taking natural antioxidant supplements during chemotherapy. The authors evaluated 845 articles from five scientific databases. The 30 articles that met all evaluation criteria, including the use of randomized trials with a control group, covered 1,964 patients with a variety of cancer types. Most had advanced or relapsed disease.

In 18 of the 30 studies evaluated, patients who received oral or intravenous antioxidant supplements experienced significantly lower toxicity than the control groups. Glutathione, melatonin and vitamin E showed the most consistent and promising effects. The only study that reported significantly greater toxicity in the antioxidant group than the control group utilized vitamin A, although these results were not surprising due to the well documented toxicities of high-dose vitamin A.

Several of the studies reported fewer chemotherapy dose reductions, fewer treatment interruptions, and less need to discontinue treatment prematurely among the antioxidant groups. The authors cited the importance of these findings in light of a recent study showing a near-doubling of survival rates for a group of colon cancer patients who were able to complete their entire course of chemotherapy.

In addition, of the 19 studies in the review that reported tumor response and/or survival rates, all but one of the antioxidant supplemented groups experienced the same or better response than the control group. No studies reported significantly worse survival or response in the antioxidant supplement group. These results were previously reported in a paper by the same authors as evidence that oncologists do not need to be concerned that supplements will interfere with the tumor-shrinking effects of chemotherapy agents.

The Block Center for Integrative Cancer Treatment, located in Evanston, Illinois, was founded in 1980 by Penny and Keith Block, MD. The Center?s research-based treatment integrates an innovative approach to the best of conventional medicine with scientifically sound complementary therapies, including therapeutic nutrition, botanical and phytonutrient supplementation, prescriptive exercise, and systematic mind-body strategies, to enhance the recovery process. Block has pioneered this “middle ground” approach to cancer care and optimal health.


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