(NYT Syndicate) -- While the role of antioxidants in preventing disease has received much attention, some researchers think the vitamins may also improve cancer treatment.

Giving cancer patients high doses of beta-carotene and vitamins C and E may protect their healthy cells from the onslaught of tumor-killing treatments like chemotherapy and radiation, say Denver researchers. Further, they contend, the antioxidants may bolster the effectiveness of standard cancer therapy.

No studies on humans back up these ideas, but in animal studies and experiments on cancer cells, antioxidants have shown promise, according to a report in the current issue of the Journal of the American College of Nutrition.

Kedar N. Prasad, lead author of the report, said more definitive data will come from a current trial of the effects of antioxidant treatment on cancer patients. Already, though, Prasad and his colleagues at the Center for Vitamins and Cancer Research at the University of Colorado Health Sciences Center believe antioxidants may become an important cancer weapon.

Antioxidants have been studied as disease fighters because they prevent cell damage from oxygen molecules known as free radicals, which are produced during normal metabolism. One recent study suggested that an antioxidant found in tomatoes might explain the link between tomato consumption and lowered risk for some cancers.

In their experiments, Prasad and colleagues found that high doses of multiple antioxidants can not only protect normal cells during cancer treatment, but can also help fight back tumors. Together with diet and lifestyle changes, antioxidants may improve standard cancer therapy, they reported.

Another antioxidant researcher, however, thinks Prasad's team is jumping the gun. While the new report is "exciting and provocative," it really only forms the base for further research, said Jeffrey Blumberg, a professor of nutrition at Tufts University in Boston.

"I think antioxidants are terrific," Blumberg said, noting that there is "compelling" data on antioxidants' benefits for the heart and eyes. Evidence of the vitamins' link to cancer prevention is not as strong, he added.

According to Prasad, antioxidants have garnered little enthusiasm among oncologists partly because they worry that the vitamins might actually protect cancer cells from free radicals generated during chemotherapy and radiation therapy.

"But," said Prasad, "these vitamins are very selective." Normal cells, he explained, are programmed to pick up a maximum level of the vitamins and nothing more, which protects them from an antioxidant overdose. Cancer cells, however, accumulate the vitamin to levels that may be high enough to stunt their growth or even kill them, according to Prasad.

Based on their experiments, as well as their observations of some cancer patients receiving antioxidants, Prasad's team recommends that cancer treatment include doses of vitamin C, vitamin E and beta-carotene.

But making cancer-treatment recommendations at this point constitutes a big leap, according to Blumberg. Experiments on cell cultures, he said, aren't enough to provide a "rational scientific basis" for such recommendations.

Still, the Colorado team's results show antioxidants may have a role beyond just the prevention of disease, Blumberg said. Clinical trials, he added, should explore the possibility.

Journal of the American College of Nutrition (1999;18:13-25)

Copyright 1999 The New York Times Syndicate. All rights reserved.