(HealthDay News) —
Supplementation with the
antioxidants vitamin E and beta carotene may cause
unexpected problems in
patients with head and neck cancer, researchers
warn.
Reporting in the April 6 issue of the Journal of the
National Cancer
Institute, investigators at Laval University in
Quebec City, Canada,
studied 540 head and neck cancer patients who’d been
treated with radiation
therapy between 1994 and 2000.
The patients received supplementation with either a
placebo, or vitamin E
and beta carotene — a precursor of vitamin A —
during radiation therapy
and then for the following three years.
Although patients were tracked for an average of
more than four years, beta
carotene supplementation in this study was halted at
one year after another
trial found an increased risk of lung cancer among
smokers who took the
nutrient.
The researchers report that patients who received
vitamin E supplements
were at greater risk of developing a second primary
cancer while receiving
supplementation, as well as a lower risk of a second
primary cancer after
the end of supplementation, compared with patients
who took a placebo.
Overall, after eight years, the proportion of
patients who were free of a
second primary cancer was similar in both groups,
the study found.
Among the patients receiving vitamin E, the rate of recurrence of head
and neck cancer or a second primary tumor was also
higher during
supplementation and lower after the end of
supplementation, compared to
patients taking a placebo.
“This cancer chemoprevention trial was conducted in
a population of
patients at high risk of second primary cancers.
There is some concern
about the generalization of the study results to
individuals in the general
population who are at low risk of a first primary
cancer. Nevertheless, our
results suggest that caution should be advised
regarding the use of
high-dose [vitamin E] supplements for cancer
prevention,” the study authors
wrote.
