Vitamin Supplementation Appears to Protect Against p53 Mutations

n PHILADELPHIA—Vitamin 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 neck cancer.”

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