Researchers: Vitamin Derivative Can Prevent Cancer

BOSTON — After nearly 20 years of tantalizing hints that vitamins or other food substances might prevent cancer, researchers say they finally have proved that this strategy can work.

By giving people a form of a vitamin, they prevented one type of cancer.

In a study being published Thursday, researchers at the M.D. Anderson Cancer Center of the University of Texas in Houston report that high doses of a derivative of vitamin A, marketed as the acne drug Accutane, prevent lung, throat and mouth cancer in people who are at high risk of developing them.

The patients had been successfully treated for one episode of head or neck cancer.

But because their tissues already were primed to become cancerous, they were highly likely to grow new, separate cancers that were more life-threatening than the first.

Accutane prevented these new cancers from forming in most patients in the study for nearly three years, the researchers reported.

The drug did not prevent the spread or recurrence of the original tumor.

Accutane has serious side effects at high doses, but experts say that if the researchers can show lower doses also work, the stage will be set for giving Accutane to people who smoke or drink heavily, and so are at relatively high risk to get head or neck cancer.

And the finding strongly indicates that other cancers also might be preventable.

Cancer specialists envision cutting the cancer toll by identifying people who are at high risk because of their genes or their habits, like smoking, and then intervene to prevent cancer by giving them vitamin derivatives or other drugs.

Dr. Peter Greenwald, director of cancer prevention and control at the National Cancer Institute in Bethesda, Md., said the new study is the first that shows such a result and ``gives us the final proof`` that the strategy known as chemoprevention of cancers works.

Dr. E. Robert Greenberg, a professor of community and family medicine at Dartmouth Medical School, said, ``It is very encouraging that it looks like there`s something beyond theoretical evidence that we might be able to prevent cancer.``

Greenberg directed a second study being published Thursday that found that another form of vitamin A, beta carotene, did not prevent skin cancers in patients at high risk of developing them.

Others agreed. Gilbert Omenn, dean of the School of Public Health at the University of Washington in Seattle, said that ``head and neck cancer and skin cancers are very different, and beta carotene and vitamin A are not the same, so it is not at all surprising that the results are not the same.``

Both the head and neck and the skin cancer studies are being published Thursday in The New England Journal of Medicine. They are accompanied by an editorial, which notes that there are 12 large studies of chemoprevention under way in the United States and five going on elsewhere.