Impact of antioxidant supplementation on chemotherapeutic toxicity: a systematic review of the evidence from randomized ........

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international du cancer." href="AL_get(this,%20'jour',%20'Int%20J%20Cancer.');">Int J Cancer.
2008 Sep 15;123(6):1227-39.
Impact of antioxidant supplementation on chemotherapeutic
toxicity: a systematic review of the evidence from randomized
controlled trials.
Block
KI
, Koch
AC
, Mead
MN
, Tothy
PK
, Newman
RA
, Gyllenhaal
C
.
Institute for Integrative Cancer Research and
Education, Suite 350, Evanston, IL, USA.

Much
debate has focused on whether antioxidants 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), selenium
(2), L-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. Copyright 2008 Wiley-Liss, Inc.