n PHILADELPHIAVitamin supplements have been shown to have a
possible protective effect against mutations of the p53 gene in head
and neck cancer, Bruce J. Trock, PhD, director of Molecular
Epidemiology, Georgetown University Medical Center, said at the
American Association for Cancer Research annual meeting. The
multicenter, collaborative study also included scientists from Fox
Chase Cancer Center and Temple University Medical Center.
The researchers examined the effects of a variety of exposures,
including vitamin supplement use, on p53 mutations in 135 head and
neck cancer patients. Questionnaires were used to assess
patients vitamin use and other data.
The regular use of vitamin supplements corresponded with
significantly reduced risk of p53 mutation, Dr. Trock reported.
Head and neck cancer patients who had been regular users of vitamin
supplements before diagnosis were only one third as likely to have
p53 mutations in their tumors as those who had not taken supplements.
This effect was especially evident in patients who took the
antioxidant vitamins A, C, or E, Dr. Trock said. In these
patients, the risk of p53 mutations was reduced 75%.
Cumulative tobacco exposure, however, was found to modify the
protective effect, with the duration of tobacco exposure being
significantly relevant. For patients who had smoked less than 30
years, vitamin supplements reduced the risk of p53 mutations by
20-fold. The reduction was only twofold, and not significant, in
patients who had smoked for 30 years or more. Adjustment for other
exposures or risk factors did not change these results.
In conclusion, Dr. Trock said, we observed a strong
reduction in p53 mutation frequency among head and neck cancer
patients associated with regular vitamin supplement use. To our
knowledge, this is the first published report of a protective effect
of vitamin use on p53 mutation.
Implications for Chemoprevention
Because of the more aggressive phenotype of tumors with p53
mutations, these results may have implications for chemoprevention.
This research, if it can be confirmed by other studies,
suggests that vitamin supplements may reduce the aggressiveness of
head and neck tumors, even if they do not prevent the onset of
disease, Dr. Trock said.
He noted, however, that this is only one study, and cancer
researchers have been wrong about vitamins before, so additional
studies are necessary before we can draw specific conclusions about a
possible role for dietary supplements in the prevention of head and
It is far too premature to be making recommendations about vitamin
use, he said, but we think this is a tantalizing bit of
evidence that needs to be followed up and could have implications for
clinical outcome, for understanding carcinogenesis, and for
developing new chemopre-vention protocols. w