A drug made by Pfizer Inc. can protect young cancer patients’ hearts from the ravages of chemotherapy and keep them from developing serious cardiac problems later in life, researchers said on Wednesday.

A study published in this week’s edition of The New England Journal of Medicine suggests the drug dexrazoxane may become a valuable tool in reducing the harmful side effects of treating children with leukemia.

There are about 250,000 survivors of childhood cancer in the United States alone and more than half were treated with drugs now known to damage the heart. Doctors give those drugs anyway because they are so effective at killing the cancer.

But the children who receive chemotherapy are eight times more likely to die from a heart-related problem than children who have not had cancer, and the rate of sudden death, presumably from heart problems, is four times higher among young cancer survivors.

Steven Lipshultz of the University of Miami School of Medicine, chief author of the study, said he had seen 50 cancer survivors - some barely adults - require heart transplants because of “the sobering reality that there’s a price to pay for a cure.”

Now, fewer children may have to pay that price, said Lipshultz, whose study was paid for by Pfizer, the National Institutes of Health and Roche Diagnostics.

The study found that among 101 children getting the anti-leukemia drug doxorubicin for their chemotherapy, 50 percent showed evidence of heart damage. But when dexrazoxane was added to the treatment of 105 youngsters, signs of damage were seen in only 21 percent.

Moreover, dexrazoxane did not appear to cut the effectiveness of the cancer-fighting drugs, although the Lipshultz team noted those findings were not conclusive. The team recommended long-term follow-up to determine the influence of dexrazoxane on survival and heart function.

Dexrazoxane, sold under the brand name Zinecard, is believed to soak up the harmful free radicals created by chemotherapy. The drug has been around for at least 30 years, although it has not been approved for this use, Lipshultz said.

In an accompanying editorial in the Journal, Leontine Kremer and Huib Caron called the Lipshultz study an “important step” toward protecting children’s hearts from chemotherapy. They added that questions about the drug remain.

Kremer and Caron, of the University of Amsterdam, said dexrazoxane had not been used in adults because of unconfirmed evidence in patients with breast cancer that it might reduce the effectiveness of cancer treatment, or that it might have side effects on the blood, stomach and intestines.

SOURCE: New England Journal of Medicine, July 8, 2004.