[ RadSafe ] Article antioxidants may not be beneficial

[John Jacobus]

Another example of the complexities of biology.

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Antioxidant supplements show mixed effects on
radiation therapy
9/21/2005
By: Reuters Health

NEW YORK (Reuters Health), Sep 21 - Antioxidant
vitamins may reduce the severity of adverse effects of
radiation therapy but may increase the risk of
recurrence of the underlying tumor, according to a
report by Canadian researchers.

Although many patients take vitamin and mineral
supplements in the hope of improving cancer treatment
outcomes, the authors point out, few studies have
examined the efficacy and safety of adjuvant
antioxidant vitamin supplementation in this setting. 

Dr. Isabelle Bairati from Laval University Cancer
Research Center, Quebec City, and colleagues examined
whether daily supplementation with alpha-tocopherol
and beta-carotene could reduce the rate and severity
of acute adverse effects of radiation therapy in 540
patients with head and neck cancer. 

Severe acute adverse effects during radiation therapy
occurred in fewer patients in the supplement group
(19.2%) than in the control group (24.8%), the authors
report in the August 20th issue of the Journal of
Clinical Oncology.

There was a tendency for less severe adverse effects
during radiation therapy at any site and overall among
those receiving antioxidants, the results indicate.
Combined treatment with alpha-tocopherol and
beta-carotene was associated with a significant 62%
reduction in adverse effects overall and a similar
reduction among patients with cancer of the larynx. 

However, local recurrence of tumor was 37% more likely
among patients in the supplementation group, the
investigators report, and was somewhat higher among
patients treated with both antioxidants. 

In light of these findings, the researchers observe
that "randomized controlled trials should be conducted
to provide clear scientific evidence regarding the
efficacy and safety of antioxidant use as adjuvant
therapies for cancer."

In an accompanying editorial, Dr. Kevin Camphausen and
associates from the National Cancer Institute in
Bethesda, MD, agree, pointing out that "the issue of
patient self-supplementation with antioxidants during
radiotherapy must also be addressed in more detail
given the results of this study."

"Without any definitive data on this issue," they
conclude, " a reasonable approach would be to avoid
unnecessary supplementation during and after
radiotherapy."

J Clin Oncol 2005;23:5805-5813,5455-5457.

Copyright © 2005 Reuters Limited. 

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"Anyone who has never made a mistake has never tired anything new."
-- Albert Einstein

-- John
John Jacobus, MS
Certified Health Physicist
e-mail:  crispy_bird at yahoo.com


		
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