News
Impact of Antioxidant Supplementation on Chemotherapeutic toxicty
Wed, 1 Oct 2008
Much debate has focused on whether antioxodants interfere with the efficacy of cancer
chemotherapy. The objective of this study is to systematically review the randomized,
controlled clinical trial evidence evaluating the effects of concurrent use of antioxidants
with chemotherapy on toxic side effects. We performed a search
of literature from 1966-October 2007 using MEDLINE, Cochrane,
CinAhl, AMED, AltHealthWatch and EMBASE databases. Randomized,
controlled clinical trials reporting antioxidant-based
mitigation of chemotherapy toxicity were included in the final
tally. Searches were performed following a standardized protocol
for systematic reviews. Only 33 of 965 articles considered, including
2,446 subjects, met the inclusion criteria. Antioxidants evaluated
were: glutathione (11), melatonin (7), vitamin A (1), an antioxidant
mixture (2), N-acetylcysteine (2), vitamin E (5), seleniumL-carnitine (1), Co-Q10 (1) and ellagic
acid (1). The majority (24) of the 33 studies included reported evidence of decreased
toxicities from the concurrent use of antioxidants with chemotherapy.
Nine studies reported no difference in toxicities between the
2 groups. Only 1 study (vitamin A) reported a significant increase
in toxicity in the antioxidant group. Five studies reported the antioxidant
group completed more full doses of chemotherapy or had
less-dose reduction than control groups. Statistical power and
poor study quality were concerns with some studies. This review
provides the first systematically reviewed evidence that antioxidant
supplementation during chemotherapy holds potential for
reducing dose-limiting toxicities. However, well-designed studies
evaluating larger populations of patients given specific antioxidants
defined by dose and schedule relative to chemotherapy are
warranted.
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